Heat is normally a symptom of some engine or combustion malaise. 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.

Cooling a car generally concentrates on coolant temperatures and secondarily oil temperatures.

The coolant heat is dissipated by its passage through the radiator which is turn cooled by the flow of air that runs through it. As this flow of air greatly increases with speed and idling engine 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.


Morgan cowls restrict the possibility of large radiators. The louvres do not improve the airflow much and must 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. They are available from Isis Imports in San francisco or 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.


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 SPAL)

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, 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 all Morgan manifolds arrive with even when new. It does not discolor as does stainless steel (which doesn't lower heat).

Make sure that the INSIDE of the manifold is coated..this is more important than the aesthetics of the outside. 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.

Curiously, I have only found one coating service in the UK or Europe..though they are common now in North America, New Zealand, Australia, and Japan.

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.

Wrapping your Headers

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 and will very much accelerate the rusting of the manifolds. They also, of course, do not improve the inner surface of the manifolds and thusly do not speed the flow of gases. They can, however, block the heat from the wrapped section.

Coating vs Wrapping

I get asked this question quite often, and there’s really no easy answer since each application is different, and everyone has a different budget. But in a nutshell, ceramic coating is the better option.

There are two issues when using a wrap that do not come into play when using a ceramic coating. These issues are thermal fatigue and moisture corrosion.


Wraps decrease under hood and under wing temperatures and because of that save other components. But they also shorten the life of your exhaust. Wrapping promotes thermal fatigue of the component you wrapped. It is a type of metal fatigue caused by repeated heating and cooling, also called creep damage which leads to premature component failure. Some owners believe that wraps help prevent thermal fatigue, but in fact, it is the opposite.

Wrap your headers and a few years later, there are holes in the piping. This can happen quicker than you might think.


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.

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.

The Thermostat

The thermostat is widely misunderstood by owners and some in the trade alike..(most often the 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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The Plus 8s Gauge's Cooling Sender
by Chris Beck and Lorne Goldman

Morgans have 2-3 sensors for coolant temperature, depending on whether the model you have is carb'ed or EFI

1. An "Otter" (UK terminology) or rad fan switch that turns on the rad fan when the coolant goes over a certain range.
2. A "thermomister" in EFI systems that reports the coolant temperaure to the ECU (engine management computer)
3. A coolant temperature sender from the engine to the engine temperature gauge on your dash.

This note deals with #3. It is a single wire affair that is behind the alternator and next to the Thermostat, where the coolant is always at it's hottest, just before it enters the radiator. Losing it when you are working in the area is quite common. It can make the gauge have weird readings or none at all, but it does NOT effect the running of the engine as the other coolant sensors will.

The wire (should be green with a blue tracer...but decades is a LONG time to keep all the original wiring!). It runs from the sensor through a hole in the inner wing  (valence) adjacent, often under the alternator. However, when unattached, the wire often falls down or can even be pulled into and through the valence hole. Trust me, it is there somewhere. You can also perhaps trace it from the other end..It merely is a simple wire that runs from sender to gauge.

The other thing to note is that  it sends a reading of the temperature of the coolant at the TOP of the engine, where it is at its hottest. Your rad fan sender is at the BOTTOM of the rad, where the coolant is at its coolest. With that in mind, you can check that they are both operating correctly after you figure out the difference (in different driving circumstances).

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.