Overheating issues

[Michelin]

Hi guys,

I have some overheating problems on my rebuilt engine on Sincar 2606. We have checked the radiator the fans, the water pump,.. and everything is ok.
So we have dismantled the cylinder heads and I have one question about head gaskets : is it normal that there is à small hole on the gasket ? It seems that the water is blocked in that aera as we can see the mark on the gasket.
Is there a possibility to have other gaskets wich improve the flow ?
Moreover, our mechanic said that there is a misaligment between the water holes of the block and the heads. Is it normal ?

Your answer will be very helpfull
Thank you very much !

[RockyUSA]

There is an article in the Jensen Monday Club tech section.

The gaskets with the small slots were designed to keep the heads hotter to improve (reduce) emissions.

I opened my gaskets up to get more flow, it cured my “afterboil” issues when the car was shut off.

You can see a bit of information in my 133-5597 thread, toward the end.

There are some other areas of the gasket that can be opened for additional flow as well.

I would open the gaskets up as much as I can. I haven’t seen a downside.

And yes, the holes /slots are not aligned from the factory.

Rocky

[Chris_R]

In what conditions does it overheat? When you are driving at highway speeds? When you are not moving, perhaps in traffic?
The cause of each might be different.

[Michelin]

Thank you for very much for your answers.
I will have a look at the article from jensen monday club.
Overheating occurs in normal driving conditions after 40 km. I have to stop due to Dashboard indication temperature. After that, I can heard that water is boiling. Il think the main reason of that problem is a bad block cleaning before engine mounting. We saw much deposit between cylinders. But we don’t want to take any risk and the expert was very surprised with the head gaskets situation.

Kinds regards
Laurent

[DPP]

I modified mine on my G Series car and have since driven it about 20,000 miles sometimes on very hot days stuck in traffic and it has never overheated (apart from the time the fan fuse blew) and I am running standard fans and radiator.

I cant seem to add a link but it is on page 10 of Restoration of 128 4430 in the members car section.

[Chris_R]

Remember, under pressure the coolant will not boil until a temperature of approx 118c - 120c. If the pressure is released then it will boil as the pressure falls, this is why you never open a radiator cap when the engine is hot as it will be under pressure. If the coolant is boiling it means the temperature must have reached that point. Have you tried to measure the temperature at different places with an infra red sensor? That would be my next action (after making sure the radiator cap is the correct pressure).

[johnw]

You do need to be careful when cutting the gaskets as Rocky suggests, to avoid them delaminating and causing problems, especially these modern composite ones. Misalignment of casting holes is normal, as is the rotting of that small slit into a larger opening, you see that on older engines. There may well be a lot of gunge in the passageways behind the core plugs. If you have new core plugs it would have been cleaned out I imagine.

We all have electric fans, make sure that they are pulling or pushing in the right direction! What does your coolant look like? There is a little brass tap at the bottom of the radiator. Maybe drain your coolant, poke the hole with wire if it is blocked. Save the coolant in a bucket, let the bits fall to the bottom overnight, and re use it. Do that a few times after drives etc. If it keeps getting bad, flush the engine with a hosepipe, just remove the thermostat and alloy elbow, flush the radiator too. Very easy to do and you could do it a few times until it all comes out perfectly clean each time, then you know to move on and find a different cause if you still have problems.

[Fishyboy]

Hi Michelin,
Here is the link to page 10 of Dave Pearce's restoration thread of 128-4430.

viewtopic.php?f=17&t=12458&start=135

Phil

[Steve Payne]

This is the link to the article on head gaskets and the narrow slots
https://members.tripod.com/~mopar_roads ... _cure.html
I have been modifying head gaskets for years and as long as you are careful there is no problem even after 100,000 miles. I open them up to the size of the holes in the heads and block.
Keeping an engine cool is all about water flow, the longer it spends being heated the more heat you need to remove, speed up the water flow and it all works so much better in our cars. High flow water pump, high flow thermostat and big holes in the gaskets and of course a good radiator.

Steve

[Andy MK1 Int]

Laurent,

There is a lot of good advice here from people who know a lot more than I do. Just a note not to make the mistake I have made. Please check that both fans are sucking cool air from outside through the radiator not blowing hot air from the engine! I had some overheating problems on the way to and from this year's international and was preparing to replace the water pump, flush out the block etc. In the end I found that the fans were running in the worng direction. A quick swap of the wires and a radiator flush and it is running cooler than ever. How this happend I do not know but it was an easy fix. That this caused a signifcant temperature rise every time I slowed the car which didn't reduce when moving again was an eye opening experience for me. Always check the simple (stupid?) things first.

Good luck
Andy

[Grant]

MichelinMan , Before you going pulling heads and opening out gaskets I just wanted to throw my 10pence worth in..As Steve said a good clear block, stat & rad is a must, I have always run Standard Fans on my cars and never had any issues, but I take the rad out(when I have 1st bought my cars) and flush them backwards if you suspect they it maybe blocked, if it's too far gone replace it, make sure the stat in is good condition if not replace it or even try and run without it ONLY FOR TEST PURPOSES, but then I have flushed my system out using household central heating flush for a good few days, letting the system get slightly warmer than running temp and then flush it all out, there are drain bolts in the side of the block that you can remove too, do that a few times with the whole system and fill with nice clean water and try it, if it sorts your problem drain and refill with distilled water 50/50 with AntiFreeze , This is what I have done and never had any issues with my cars getting hot and I've been messing around with these for donkeys years ..good luck My Ole Fruit ..Grant

[DPP]

The problem with our cars is anything could have been done to them in the last 50 years.

I was carrying out a cosmetic engine clean and paint on an engine that had a top end rebuild not long before it came to me, I was not happy to see lots of sealant around the coreplugs and decided to replace them even though they were new. To my horror when I removed them I found another set which had just been punched into the heads. It would have been a nightmare to find why the engine was overheating had I not found this issue.

[Michelin]

There is an article in the Jensen Monday Club tech section.

The gaskets with the small slots were designed to keep the heads hotter to improve (reduce) emissions.

I opened my gaskets up to get more flow, it cured my “afterboil” issues when the car was shut off.

You can see a bit of information in my 133-5597 thread, toward the end.

There are some other areas of the gasket that can be opened for additional flow as well.

I would open the gaskets up as much as I can. I haven’t seen a downside.

And yes, the holes /slots are not aligned from the factory.

Rocky

Thank you very much for your answer. This is very helpful.

[Michelin]

Thank you very much for all your answers. I have given all your advice to the mechanic and I am sure this will help him.
Kinds regards
Laurent

[Michelin]

This is the link to the article on head gaskets and the narrow slots
https://members.tripod.com/~mopar_roads ... _cure.html
I have been modifying head gaskets for years and as long as you are careful there is no problem even after 100,000 miles. I open them up to the size of the holes in the heads and block.
Keeping an engine cool is all about water flow, the longer it spends being heated the more heat you need to remove, speed up the water flow and it all works so much better in our cars. High flow water pump, high flow thermostat and big holes in the gaskets and of course a good radiator.

Steve

Thank you Steve for your answer. I think, il will follow your advice to modify the gasket. Do you know what is the best kind of gasket to do that modification ?
Laurent