Heat is often a symptom of engine or combustion malaise. So any discussion on cooling must start with the premise that the reader has ruled out poor timing, too lean an air/fuel mixture, bad coolant, a radiator or cooling system blockage, a faulty water pump, bad combustion, poor lubrication, a lousy rad fan, a malfunctioning sensor, a bad thermostat, an imprudent camshaft selection or "badge" blockage. Sadly, some of these issues can come straight from the Works, depending on the year and model. As emissions regulations become more severe with the passage of time, air/fuel mixtures began to create much greater heat. 

Coolant heat is dissipated by its passage through the radiator which is turn, hopefully cooled by the flow of air that runs through it. This flow of air greatly increases with speed. So an idling engine or one in stop-and-go traffic gets hotter than a cruising engine. Systems to deal with a stationary or slowly moving car must compliment the systems used to cool a cruising car. That makes the fan as important as the radiator.

Morgans have an inherent problem in this area, as the engine bay was designed for 36 bhp engines. We must rely on the best of other measures.

WATCHPOINT FOR PLUS 8s: There is an immense amount of nonsense about cooling this lovely engine. :(  All engines and their fueling systems have a temperature range they are meant to run at.
Plus 8s came in two basic versions, Carb'ed and EFI. The former runs lower temps becuase of the regulatory time they were installed and the fact that carbs are inefficient enough to that the uncombusted petrol  cools the engine rather than powering it. EFIs are more efficent producing a more complete burn. So the Plus 8 thermostat is set to open at 82C for carb'ed cars, EFIs open at 88C. This is additionally confusing with Morgans and many have their rad fan switches at the bottom of the radiator, where the coolant is coldest and yet the dash temperature gauge is installed at the top of the engine, where the coolant will be its hottest. (I experimented and had rad fan switches put both at the bottom AND the top of the rad.) The temperature difference is 4 to 5C and can vary more (or less) depending on whether one is stationary of moving.  Of course, the temperature reading is best taken from the top, but one gets used to a chosen placement. 
I like my BIG fan (early Morgan fans were inadequate..even the early Spals) coming on when the gauge reads about 98C, if the rad fan switch is placed at the bottom of the rad and 96C if the rad fan switch is at the top. BTW, the temperature sender is just to the left of the thermostat housing if you are standing in front of the car.  It should not be confused with the EFI temperature sender.

All cars MUST run within their desired engine temperature range indicated above. However, owners often swear they have the craziest temperatures given by faulty gauges or, most likely, bad connections at the coolant temperature sender or gauge.
Once a year, remove the wire to the sender, clean the blade on the sender, and make sure your fitting is tight and can not wiggle.  Running temperature for a an EFI Plus 8s is around 91-98C. If it is under or over that, you have a problem.  It could be, as described, merely a bad connection or it could be worse. The later EFI vehicle (like GEMS Plus 8s) can be very sensitive to lower temperatures, which will eventually force them into limp-home mode, requiring a computer reset in a world where such systems have not been installed by Land Rover for more than 22 years, which is older than many of the LR dealers mechanics! 


Morgan cowls restrict the possibility of large radiators. And the bonnet The louvres do not improve the airflow much. They should be considered decorative. The flow of air is funneled through the grill or from under the car. This being the case, the following aids may help when moving.

1. Especially for 4/4s and Plus 4s the areas between the radiator and the cowl sides should be closed off to close the escape route of the needed airflow and force it through the radiator.

2. Install an air "dam" or rubber mat deflector underneath the car to force the cool low air (the lower the air from the ground the cooler it will be) up into and around the radiator.

3. Even better than 2. install an air scoop that will funnel large amounts of cool low air into the front of the radiator. A scoop can double the air flow into the rad. There is a Morganesque version designed by Maurice Owen and Bill Fink that replaces the original scuttle (the piece at the bottom of the grill cowl attached to the wings) with a new scuttle shaped "S" funnel that forces the air up from under the car and into the rad. It is remarkable how well these scoops can work (though only when moving over 40 mph). They are available from the Morgan Factory.

4. Avoid "badge blockage" which occurs when our affection for badges on a badge bar and badges on the grill create a significant blockage of the free flow of air through the grill to the rad.

5. Be careful of your placement of your license plate...if you are  unfortunate enough to live in a jurisdiction where front license plates are required try to place it to the side rather than the center of the car if possible. A central placement of the license plate blocks the flow of air under the radiator and makes an air scoop impossible and prejudices even a simple air deflector.


Here is where the fan comes into its glory. When moving slowly or when stationary the radiator does not have enough speed induced air flow to cool well. If these conditions continue, the car will overheat. The solution is to artificially create an airflow when needed with a fan. Obviously, the higher the power of the fan the more the airflow and the greater the cooling ability you will have when needed. Morgan fans are not famous for power but many good replacements are available. (see upgraded SPALs)

1. Do not install a fan mounted in front of the radiator. They are an easy install and inexpensive but they create the problem they are supposed to resolve. They block the airflow to the rad which contributes to the overheating and then they come on in effort to cool the rad to the point where they can stop and block the airflow again.

2.  Install the fan to operate on a radiator thermoswitch (if you don't already have one installed). This item switches the fan on at a certain temperature and off at a lower one. You can also install an manual switch override that forces the fan on regardless of coolant temperature to deal with a heating situation before it develops fully. Check with your supplier if you require a larger relay switch for the fan you purchase.

3. Remember that all rear mounted rad fans PULL air through the radiator. If you see your fan pushing the air back towards the radiator then simply reverse the wire leads to the fan and recheck the rotation.



Morgans are sporting old radiators, some as old as forty years. Their engines do not function as they once did, greater friction than originally is the rule and their radiators are no longer up to the original state of the engine let alone today's state. A better radiator improves cooling whether stationary or moving, but what is a better radiator? Here are some answers;

1. You have had your original radiator re-cored or you have had the coolant flow system of the radiator and the cooling facade and fins renewed. The rad returns (hopefully) to its original cooling abilities. The drawback here is whether the original cooling capacity of the radiator is sufficient for the present state of the engine. You have ignored the benefits of technological progress in the last forty years and you have used the old rad as a base which may be less than a solid foundation.

2. You have purchased a radiator larger capacity than the original though it is conventionally designed. The only drawback here is the technological one noted above and any loss of space considerations.

3. You have had an technologically advanced core installed to replace the original. A good option..but at this point why not go all the way?

4. The ultimate...a high tech aluminum radiator.  See An Aluminum Radiator for Your Morgan.


For some time,(three decades and countin) there has been an option increasingly offered of coating your manifolds or heddars with a ceramic based compound that very much lowers the heat of this part of your exhaust system..a prime radiator of heat. Essentially the a choice of colors or effects,  is sprayed on your clean sandblasted manifolds and then baked. It is inexpensive and aethetically very good looking, replacing the rust that many Morgan manifolds arrive with even when new. It does not discolor as does stainless steel (which doesn't lower heat) though I WOULD RECOMMEND A CHROME FINISH BE AVOIDE as it cannot withstand temperatures as high as other finishes.

ALSO!! Make sure that the INSIDE of the manifold is coated..this is more important than the aesthetics of the outside. This muchly makes the pipes better able to contain the heat and high heat moves faster, ejcting the high exhaist gases faster, which is a boon. There are a number of companies in the field and some can be found in the GoMoG General Parts Directory. Be careful of some of the better known firms which coat their products in bulk lots of many customers at a time, leaving a orange-peel effect to the finish.

N.B. Please ignore the claims of massive horsepower increases. These are largely "pipe"-dreaming fancies...though a cooler engine can produce more power and leaves more room for "tweaking"  than one which is already running hot because of an inadequate cooling system.

Wrapping your Headers (The poor man's solution!)

Many people still use heat wraps to lower their engine bay temperatures. Essentially, these are a wrap insulation which must be tediously wrapped around each exhaust branch. It is considered by many to be unsightly, quikcly filthy and will very much accelerate the rusting of the manifolds if they are mild steel. They also, of course, do not do anything for the INNER surfaces of the manifolds and thusly do not speed the flow of gases as much as they should. They can, however, block a bit of the heat from the wrapped section. This is merely a comfort to sweaty drivers...not much of a engine benefit to it.
WATCHPOINT: Actually the very best solution, technically, is coated mild steel, (which I learned to use if I can find it). So few bespoke exhaust makers today deal in mild steel. Happily, Morgan Plus 8s installed branch manifolds from 1976-1986 as standard and I fit them to all my Morgans. Stainless steel is embrittled by the process making it and if you are cermaic-coating them as recommended, rust is not a factor. That means an impact at the rear or at an unprotected section that extends (shudder) UNDER the chassis will crack ss more easily or ruin your heads, requring a repair of those threads.

Coating vs Wrapping  & Engine Basics
by Lorne Goldman

Many people still use heat wraps to lower their engine bay temperatures. Essentially, these are a wrapping insulation which must be tediously wound around each exhaust branch. It is veryu unsightly and will very much accelerate the rusting of the mild steel. They also, of course, do not insulate the INNER surface of the manifolds and thusly do not speed the flow of gases. They can, however, they do block the heat from the wrapped section somewhat. In most of the workdld, they went out of fashion 30 years ago.

We all know that engines get quite hot. Does this matter?  The answer is yes. Cooler engine temperatures increase efficiency from the radiator, transmission etc and produce more power. On the other hand, higher engine temperatires also produce a more complete "burn" of the fuel, lowering emissions. However, engines also have a specific temperature range where they are most efficient all round.  Most engines like to operate between 180-205 degrees F (carbs) and 197-206 degrees F. (EFI)  These ranges are reflected in the opening temperature of the thermostat and the on/off temperature of the radiator fan switch.
If we do a better job of keeping the heat of the engine in the exhaust manifold, downpipes, headers, and so on, than we can have that exhaust escaping out the back of our exhaust pipe instead of escaping into our engine compartment, and with a Morgan, into the cockpit theorugh the firewall and because of the configuration of the Morgan, with heat rushing into and up the gearbox cover...heating your footwell and thighs.  By removing excess heat from under the hood we will allow our car radiator to not have to remove as much heat from the engine. By keeping the engine in an environment that is cooler, we can bring our operating temperatures down much easier.

Better Exhaust flow

When you coat your exhaust, not only are you keeping the heat inside the exhaust so that it exists out of the vehicle, but you are also increasing the flow of that exhaust.  Significantly less so with wrapping. By keeping the exhaust gas heat in the exhaust gas itself, it will keep the exhaust moving at a higher velocity.  As the hot exhaust gasses cool, their velocity actually slows and you loose flow.  So not only is coating your exhaust good to lower under hood temps, but it also has a power benefit.

Exhaust Coating Adds Horsepower & Torque

On the other hand, the cooler the air going into the engine, the denser that air, and the more air we can shove into the motor. Moore air, more more horsepower and torque we can make. The limitation of an engine is the amount of air it can process..NOT the amount of fuel we give it. By keeping our under hood temps down, we are able to keep our intake tract and potentially our intake manifold cooler.  This allows us to shove denser cool air into the motor.  Also with the exhaust retaining its heat/energy, it will have a higher velocity and flow better.  This also helps us make more horsepower and torque.

Trust me, on a dyno it is easy to see the importance of heat retention.  When you do the first dyno pull on a car and establish where the car makes full boost, you will notice that if you do several pulls immediately afterward, that the car will make full boost even faster. This is because you have now built up a bunch of heat into the manifold and turbo.  Because of this built up heat/energy, the exhaust gasses will loose their heat much slower allowing all of that energy to be spooling the turbo. By wrapping or coating your exhaust, you will essentially be doing the same thing by helping to trap that heat in the exhaust flow.

High temperature ceramic coating my exhaust or heat wrap it?

Ceramic coating is infinitely better than exhaust wrapping..especially if you have using mild steel rather than stainless exhausts.

WATCHPOINT: Stainless steel is susceptible to embrittlement. When that happens, they lose their ability to flex and crack instead. As the ONLY advantage of stainless steel is that it does not rust, (after all it discolors very quickly..a sure sign of embrittlement). Embrittlement happens to stainless steel at constant temperatures of 350C+. Your Morgan will produce exhaust temperature highs that will be much more than that. The ideal exhaust pipes are ceramic coated mild steel.

Are there any negatives to wrapping an exhaust?

Yes.  When wrapping an exhaust you have to be very careful that you are wrapping the exhaust as tight as possible.  Because of the constant heating up and cooling down of the pipe, the wrap can work its way loose over time and loose its effectiveness.  If the wrap job is done properly (so every 8-12” re-enforced with a stainless ziptie to keep it tight) than it will do fine.

The other negative isthat wraps get wet.  It traps moisture and causes rust problems on the exhaust if it is mild steel.  For this reason we strongly suggest that you are wrapping stainless steel exhausts. Hopefully on a performance car you are using at a minimum stainless 304 for all your exhaust needs.  If you are doing an all out build and don’t want to worry about cracking or exhaust performance, than putting up the money for stainless 321 is a great choice.

If you have a cheap manifold or exhaust piping (some Morgan dealers sell them), then I would not spend the money for wrap or coatings.  I would first start by getting a quality made exhaust or manifold.  You will see many people that won’t wrap their exhausts because it “caused the manifold to crack”.  Moisture retention in the wrap  causes cracking by generating differing rates of cooling where it’s thicker in some places than others, causing distortion and then cracking.

Moisture is the second issue with exhaust wrapping. The wrap will actually pull moisture in and keep it there, holding it against the component, which speeds up the corrosion process. Ceramic coatings are self-sacrificial in design, meaning that they will corrode/rust/oxidize before the substrate underneath will. It’s a good idea to go with a coating company that offers a warranty, be careful of companies that only cover 'rust-through', meaning that there has to be a hole in your exhaust before it will get covered!

Coating the Exhaust

The best option to manage heat is to have your exhaust ceramic coated. The coating actually bonds to the substrate (at about 10,000 psi) and prevents the heat from soaking into the substrate. If you get it done right, the rate of expansion of the coating will match that of the substrate, or the metal your manifold is made of. Your exhaust component can usually be coated on the inside as well, giving it thermal and corrosion protection inside and outside. A vast improvement over wrapping.

It’s also a good idea to go with a company that creates/manufactures their own coatings, not one that just buys it from an online coatings store and slaps it on. There's a lot more to the application/preparation than you would think, and if a company has the resources to manufacture their own coatings, odds are they’ve been in the game a long time and have the processes to near perfection. The downside to ceramic coatings is of course the cost. You can get enough wrap to do most of your exhaust for around $50-$100, compared to a full system getting coated for around $500. You get what you pay for.

Top quality ceramic coatings can reduce engine bay temps by over 50%, and the more common cer-met or ceramic-metallic coatings can reduce temperatures from 30%-40%. Another added benefit is that you will see power gains anywhere from 3-5% by keeping the exhaust gas velocity up. Increase spool-time in a turbo system, and increased scavenging is another benefit of the increased exhaust gas velocity.

So, when the time comes to do some heat management, do some research for yourself, look at your budget, and determine which direction is best for you. If you can only afford the wrap at that point in time, get it so you don’t cook the rest of your components in your engine bay, just keep in mind that it’s a “quick fix” and get your components coated when you come into a bit of cash.

1) Reduces under bonnet temperatures.

2) Improved gas velocity when the coating is applied inside of the pipe.

3) Prevents the metal from oxidisation and rust.

4) Is impervious to coolant, oil and brake fluid.

WATCHPOINT national habits: Ceramic coating has become the goto exhaust treatment in most of the automobile affectionato world. Australia, Canada, the USA. Exhaust wrapping is very much the poor man's solution there. However, it has never caught on in the UK or Europe to the same degree. I feel that this is because the first purveyors of ceramic coating charged SO much that they killed that market for themselves. Prices overseas are MUCH cheaper. But in every country, you will find habit rules rather than common sense. The trick is to rely on your logic. There are DIY systems available in the UK at a much lower price.

WATCHPOINT Ceramic coating color: There is no contest on aesthetics. Exhaust wrapping quickly becomes filthy and thusly characterizes the engine bay. Stainless steel quickly turns brown/purple. Ceramic coating can be chosen in any color, though I would caution you against a "chrome" look in ceramic coating as it quickly goes opague, a dull bluish grey.

The Thermostat

The thermostat is widely misunderstood by owners and some "experts alike..(most often the amateur race crowd). Beware. They believe it has something to do with controlling temperature overheating. It does not.  Those who suggest it does, should be avoided. Their logic is faulty. To forestall objections, I will place links below of others hoping to stop engine damage and the confusion the misguided cause.

Each engine has an ideal running temperature, a small range that is excellent for engine block health, the fueling system and environment. As well, running with a cold engine is a no-no..especially at start up. To create that range and heat to it quickly, engines use automobile thermostats. This is a small heat responsive valve that takes the cooling system on or off gradually by slowly blocking or  opening the coolant flow at a predetermined temperature set at the low end of the desired ideal running range. At startup, by blocking coolant flow until the lower end of that range is reach, is forces the engine to heat to the proper running temp quickly. Once the lower end of the range is reached, it will open, putting the cooling system online. If the engine reaches the top end of the range, the rad fan comes on, presumably preventing the engine from overheating. T he racing community will often try to force a cooler mixture (to create a bit more power in an environment and game that has no emissions rules). 

For some reason (aka nonsense) people are wrongly taught that the automobile thermostat is somehow a device that can be used to COOL a car????? This is anything but true. It is a device that protects the car against overly cool temperatures that damage it and hurt your fuel mileage. This is especially important for later (post 1995) EFI cars. If you have overheating problems, look instead to the equipment you use for cooling, namely the radiator or rad fan efficiency or the rad fan switch. Do not suppose that a problem with high temperatures is dealt with by fiddling with the low end of acceptable temperatures.  Makes no sense.

The only result of a lower temperature thermostat is to force your car to take longer to reach its proper running range. At worst, it will allow the engine to run at unhealthy termperatures for longer. It will not cure your over-heating issues

WATCHPOINT: Carb'ed engines often run at a lower range than their EFI counterparts. This is why they are less fuel efficient. For example, the Plus 8 runs a thermostats with an opening temperature of 82C with carbs but 88C with EFI.

STANT (Thermostat Manufacturer)
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Plus 8s & Cooling (et al) Component Confusion (1995-2004)
by Lorne Goldman

The Confusion.

In the last 2 days, my inbox has been filling with cooling questions from Plus 8 owners. There must be a forum or "guru" somewhere feeding that part of the community with erroneous information. This is understandable as Morgan Plus 8s departed from the then current Land Rover norms from 1989 on. It is further complicated for owners and their mechanics as, for a period during that era, Morgan used a different fueling system and ignition system for cars they sent overseas (the majority of Plus 8s from 1999 to 2004)  from the cars they sold to the UK and Europe. So not only are the Morgan setups different from Land Rover's, they are different from each other!!  The confusion gets worse as Land Rover was selling diesel models as well!  If you look for a part, mechanic or owner, and you give the engine maker, model and year, you will often be giving the wrong part. And then who checks the supplied part?!!

Let's start with basics. Land Rover had a number of V8 engine variations and three (3) fueling & ignition systems in the period from 1994-2002. 13CU Hotwires(1987-1988) 14CU Hotwires in 1989 and finally 14CUX HOTWIRES, 1990-1995. The Land Rover GEMS era spanned 1995-1999. Finally, Land Rover moved to BOSCH MOTRONICS 5.2.1 in early 1999-2002.  This last system was NEVER used on Morgan Plus 8s. The Morgan Compnay ceased producing Plus 8s when they could no longer source the correct version of GEMS and they ran out of the safety bag system.

Morgan, on the other hand, would delay moving to new fueling/emissions systems (for reasons of costly testing) as long as they could. AND new emissions and safety regimes have long grace periods, varying from country to country. As well, grace periods and emissions/safety standards vary from jurisdiction to jurisdication. During this period, UK/European standards were lower than Overseas. Morgan used the FLAPPER (Bosch L-Jetronics) 4CU system until late 1990. Then they switched to the 14CUX HOTWIRES from then until very late 1999 in the UK/Europe and until 1996 Overseas. Overseas. Morgan used a bespke version of GEMS from 1998-2000 (though these dates are misleading as Morgan labelled later cars earlier to allow the importation). From 2000, all Plus 8s, European/UK or Overseas, used the standard GEMS system that the Land Rover had used (see above) from 1995-1999!

You can see how easy it is for suppliers, owners and even experts, to get component confused. Only that era's Morgan cogniescenti have an easy time with it. Later and earlier pros and amateurs simply make mistakes. Of course, in most cases, the wrong component simply does not fit or work and the only things lost is time and frustration. However, in some cases, the wrong components fit!! This creates long term problems. Let's examine the issue of cooling components, which are interchangeable among all versions of the Plus 8 from the early Buick 215 to the last 4.0/4.6 LR blocks, most specifically the rad fan switch and the thermostats.

As noted above, the happy running temperature range of a engine/fueling/ignition combination is fairly small. This is the range where the engine runs it's most efficiently  and where internal damage can best be avoided. Lower temperatures may produce a bit more power at lower rpms, but the engine innards will reflect the lower temps in unhelpful gunk and goo.Trust me I have seen too many of those!  IMHO, it is advisable for racers only who need the power, couldn't care less about emissions and are always running at high gunk-eliminating rpm. Higher tempertures provide a better "burn" and mileage but increase the compression chamber stress on the block.  For these reasons, you want to make sure your temperature range is strictly reflected in your choice of thermostat and rad fan switch. Outside of the risks to those of us with annual emissions testing, the longer term consequences of getting these two items wrong are unpleasant.

This confusion on components makes this a regular problem. The Land Rover change from a 3.5 to 3.9 block weakening the the block integrity and as combustion chamber temperatures were incrementally increased over time, they ran into a plague of slipped liners and cracked blocks..ultimately causing them to abandon the engine entirely. RELAX !! The low weight of a Morgan Plus 8 does not create enough of load on the engine to make these failures a Morgan experience. Why I mention it is because Land Rover attempted to address the problem (unsuccessfully) by trying to lower the block temperatures with the advent of their new fueling with GEMS engines (1995) and continued this with the Bosch Motronics. They dropped the EFI V8 cooling range with GEMS from the HOTWIRES by 4C (that is a lot). With the Motronics they went further, with the thermostat opening at 6C cooler but upping the coolant presure from 15/16psi to 20psi!! But nothing helped.

In Conclusion

So who should you ask what components to buy and how your Morgan of the era (1995-2004) should be behaving? If you blithely state to a supplier that your Plus 8 is the same as a Land Rover V8 Discovery or Range Rover, give them the year, you will get the wrong component. If you ask the question of savvy UK Morgan supplier for a Overseas Plus 8, you will most likely get the wrong part. In reverse, if you ask an Overseas Morgan expert for a part for a UK Plus 8, you will also be ill-advised. Asking Land Rover people people is almost always a sure error and even those who have "Morgan parts" listed by year on their computer are invariably wrong. Auto supply computers are most often mistakenly programmed for Morgan with Land Rover suggestions. I have even come across Plus 8ers with V8 diesel parts, running with a 80C thermostat!!!!!  The temperature gauge is not a guide as few owners regularly check its connection on the engine, which has a tendency of rusting a bit, thereby prejudicing its reading on the dash guage.

The consequences of using the incorrect components in the engine area the cooling area can be sad. The car cannot achieve its correct running temperature, the milegage will suffer and the engine innards will become filthy. You can consult the block number to see what the version you have, but your best bet is to ask someone with knowledge what Land Rover and year your Morgan Plus 8 matches. Be very wary of who you choose. For example, if it is someone who tuned engines for racing that might be an error. I have heard that a former Morgan racer preparer recently advised a forum to use a 80C thermostat!!!

I will make it easy, for a starter, in this area. ALL EFI Plus 8 Morgan should be running with 88C opening thermostats unless they have a GEMS Plus 8 when a 85C (+ or - 5C) thermostats could be used. If your car cannot achieve these temperatures, you can assume that something is amiss as the cooling system is, de facto, shut off until these miniums are reached.  Here are snippets from the relevant Land Rover Manuals.