Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) 4/4 1948 Overheating after some work done......

Thanks for your answer, good idea, I will do that too.

Hello Gon ,
if you have checked the temperature with a laser gun, and that is ok, then you must be careful of false air. too small nozzle or carburetor/manifold gasket problem let the temperature rise.
I had an hole in one of the pistons after 2000km after an rebild of an carburator .

Stefan

Thanks Stefan for your comments, I will include your comments in my questions for tomorrow morning.

Have a nice evening,
Gonzalo

Hi guys, I have more information. I noticed that the oil pressure is significantly higher than used to be, (before I rebuilt the distributor), and the radiator steams a little bit after a short ride. The radiator was rebuild 6 months (supposedly)

Could the new bushings of the distributor improve the performance of the oil pump so much?

I am a little bit confused, I bought the Morgan 20 years ago and it never gave me any headache.......

Thanks in advance

Is the oil pressure gauge driven electrically? If so, as in my previous post, I'd strongly suspect the instrument voltage regulator.

Is it possible that the refurbished distributor is causing an oil flow restriction? Remember that it is the oil system than removes the heat away from the bearing surfaces. The heat dissipation is greater and more important than that done by the water coolant.

All I can suggest is making a methodical analysis of when the overheating symptoms started and any change(s) immediately prior to this.

This is some information from my friend John in Oz , who owns 2 Series 1 4/4s and know more than most about this particular breed.

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It's almost impossible to trace something like this without seeing the car, but there are a few things you might pass on to him possibly.

First, the temperature gauge is the capillary/bulb type and is independent of the electrical circuit. It will even register when out of the car (mine once registered 50 degrees in my garage on a sweltering day when it was out for something or other). They are generally fairly accurate.

Next, running temperature for these vehicles is normally around 95 to 98 degrees C. It may register a bit higher just with water as a coolant than with an ethylene/glycol antifreeze mixture, not because it's running cooler with the latter but because water is more efficient at heat transfer if you can follow the "Irish". Unless there's a problem with cold weather and the danger of freezing it's best to run with pure water with a bit of inhibitor added.

But the level of water in the radiator has a big effect on cooling. The overflow pipe has a T junction on its end with a spring loaded ball valve in it. The system operates on around 2PSI pressure. The radiator should never be filled right up, but only to just under the bottom of the T valve. This will put the water level around 2" below the top of the radiator cap. If you fill to the top the car will run quite a bit hotter. Given his mechanic added water this may be a cause but it should have started to settle down by now if he has been driving the car.

These are all the simple things. Given it was running OK before, the only other suggestion I can make, seeing the distributor has been removed, is the timing. It should be set to TDC at rest. There's an arrow on the flywheel to assist this, but as there is no cut-out in the top of the bell housing to see this (unless someone has added one) it can't be done on 1 or 4 cylinders. (You have to line it up at the bottom through the drain hole and do it on 2 or 3). This won't be needed as it's running, but he should do it by road test, i.e. pulling away from a fairly low speed in top and gradually adjusting the distributor until the engine is just pinking then ease off the smallest amount. Even when set at TDC resting this should be done.

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Good luck and I hope this helps.

Thanks David and Andy for taking the time to answer back. Andy please thank John, this is great information.

Here is more info: This morning I took the car to the Mechanic, since it is so close to my home the temperature only reached 90 C. We measured the temperature of the engine with the laser gun, and as John stated, it was very accurate and consistent with the instrument reading.

About the higher oil pressure. I forgot that I changed the oil for a new brand that I was recommended: MOTUL Mineral Classic Oil SAE 50, for engines before 1950. The mechanic who took care of it for 20 years and specialized in British cars told me that it works very well with these engines. The new oil has higher viscosity and this is the reason for the oil pressure improvement. Has anybody used this oil before. It was not easy to find it in USA but I got it....

Now the new mechanic is taking care of the car, he is going to start from the timing. I hope I will get it back by Wednesday, I will keep you guys posted.

Thanks again for all the support. I really appreciate it.

Best,
Gonzalo

Hi Gonzalo, It appears that you may have traced the source of the change in oil pressure. As far as my understanding goes, a 50 SAE oil is a good choice if your ambient temperatures are generally high. It is what would have been recommended in the UK as a summer oil.

Motul is a well respected oil manufacturer.

Good luck with tracing the tempurature problem. Regards, David.

Thanks David for your answer.

I am glad to read that MOTUL was a good choice. The car used to be in South America, where the winter can be cold, but now it is in Miami, US and I was looking for the right oil for the tropical weather.....anyway I am not planing to drive the Morgan in the hot summer days (from June to September).....

As you mentioned, the oil pressure it seems to be fine. Now let's hope that the temperature will go back to normal. I will keep you posted.

Best regards, Gonzalo