OVERHEATING ?

[Deleted]

Hi, Confused here in Norfolk.
Recent purchase of a one owner 1968 3.5 saloon has revealed overheating problems. Several avenues of support and advice have opened up, but I am still anxious.
It was visibly evident that the engine was getting too hot by the gray paint on the inlet manifold all cracked and flaking, and on the rocker covers. Removing the rocker covers revealed burnt oil which had carbonised.
We assumed that it was a head gasket blown and was boiling the water and forcing it out which is common on most vehicles with the same ailment. So we examined the radiator and it was clear that it was badly silted up and full of gunge etc., We removed it and it's gone off to be re-cored (3). We took the water pump off and replaced it with the new extra vane type, removed the inlet manifold, cleaned all the gunge and rubbish out of it etc., and are ready to re-assemble evewrything.
HOWEVER !! We were advised to prove or disprove the head gasket
by applying a compression tester to each spark plug hole.
We were told that if a gasket has blown in to the water jacket, the gauge would go up to 150/180 lbs pressure and then start to fall away as it leaked out. We tested each pot and 7 were spot on with no fall in pressure. The 8th one revealed a pressure of 85 lbs only. We were advised to pour some oil down the plug hole and try again. This only made a marginal difference and we were told that means it's probably a pitted or ill fitting valve seat and to fit new tappets and push rods.
These are now on order from JRW.
All this is to try and avoid taking the cylinder heads off with the engine in situ, which we were advised again was a horrible job.
Why we are confused is because it says in the workshop manual that if a compression test reveals a lower reading, it means that the gasket is faulty between the adjacent cylinder
Who is right ?? We were told that head gaskets blowing was rare on these engines ? Should we re-assemble ? or bite the bullet and take the head off ??
Mike

[Phil Nottingham]

Are you sure its overheating - cracked grey paint and carbonised oil in the rocker covers is extremely common on little used neglected engines!!

Overheating on neglected engines is also common caused by furred up rads and blocks.

Most "mechanics" overlooked the blocked manifold coolant vent that suuplies the small rubber bore tube going to the top of the radiator - its dead easy to check as this tube should get warm very quickly as water flows through it. It can be very awkward to unblock.

PS gaskets do easily blow but into the V so that the oil is ejected abruptly!

As I have said overheating is very common and easily solved if you go about it probably - its been covered endlessly on these page so set search for a couple of years and settle down to read all about it

Good luck and welcome and let us know what happens

[Smallfry]

I agree with Phil, cracked paint and carbonised oil VERY common. You say you don't want to remove the heads.......but if you are going to renew the lifters and pushrods (although I cannot for the life of me see why) you are already three quarters of the way there. You will also find that if the heads are full of sludge, the engine "vee" where the lifters live will be even worse. This will need very careful cleaning to avoid any falling into the sump.

If you are going to all this trouble, make a careful check of the camshaft lobes, as you may well find that one or more are nearly worn away. This can also be a reason for low/no compression, as the inlet valve may not be opening enough to allow any air in to actually compress !

I think you will find your overheating is due to blocked waterways or radiator, or the vent at the top of the inlet manifold that Phil has mentioned.

[Deleted]

It does sound like your going the long way round mate. the 1st thing i would do is get it runing again and go buy a head gasket sniffer tester forn Halford etc and do a sniffer test. it takes 5 mins to do and if you dont have a headgasket fault it will save you taking off the heads. The other way of doing it is to do a pressue test on the cooling system but this is more involved but still worth wile.

hope this helps

good luck

[Deleted]

Thanks Guys, all your advice is appreciated. To clarify - inside the vee looking at the cam and lifters etc., it is immaculate. No sludge or muck or any wear on the push rods, cam lobes, or tappets. Incidentally, the advice was to only replace the tappets and lifters on the low compression pot, not all of them. The fact is that the rad was in a bad state, and the inlet manifold and the waterways etc., were virtually blocked up. I now feel that changing the water pump, the rad, and cleaning everything out will be the answer. I will now put it all back together very carefully and see what happens !! Incidentally, no one has come back to me telling me where I can get "Red line Waterwetter" in the UK ??
I'll post a reply next week telling you all what happened !!!
very best regards,
Mike

[Deleted]

I have been haunted by overheating problem on 3.5 for last 9 months - realised yesterday that the problem is that the rad cap is not sealing properly due to the rad neck being worn on the bayonet.
As pressure builds slightly the pressure is released, the water boils and is shoved out of the overflow
I suspect it when I swapped the rad for a recored spare one I had acquired but i didn't connect the events as the car was not used much for a while after the rad swap.
Fill the cooling system, start the car and wait for it to warm and listen for a hissing sound from the rad cap.

[Phil Nottingham]

SEE OTHER POST

I got some Redline for my P2 from Holdens MO - beware it will find every little hole that ordinary antifreeze will not. It does work very well but then the P2 cooling system has a design fault

[Smallfry]

Try Demon Tweeks for Redline products. I have not found anywhere cheaper.............yet !

It will help your problem a lot, but its a waste of time unless the system is in good condition, and CLEAN.

[Deleted]

Try this link chaps:
www.fluke-motorsport.co.uk/product_info.php?products_id=155

You can also buy Redline Lead Substitute........