Cooling system

[ukbiggles]

Hi all

About a year ago I raised a thread about a cooling system problem. Essentially, the car ran fine up to 80 or 100 miles or so, but when it cooled down, not all of the coolant was returned from the expansion tank (standard Mk2 cooling system). Helpful people suggested that there was an air leak in the system or it was a sign of early head gasket failure.

I am a novice mechanic so wasn't prepared to go the whole hog and take the heads off, particularly as there was no other symptoms ie no water in the oil, temperature always stayed pretty normal. So I started with the easy stuff, looking for air leaks in the hoses, replacing them all, even the metal pipe part of the system. No difference. Had the radiator and expansion bottle pressure tested and both were OK.

So since last year, I've just put up with having to siphon coolant from the expansion tank and put it back into the radiator. I then started to see some coolant in the V after a run, so have come to the conclusion that I should look at the water pump and inlet manifold gaskets.

Having taken the manifold off, what is the best way to remove the old gaskets from the heads without causing any damage around the ports and water channels?

Also, on reassembly, I've looked at Rimmers little video on how to refit the manifold using silicone etc. Does anyone have any good approaches to how the water pump gasket should be fitted. Silicon sealant or some way of getting the best seal.

Thanks in advance

Cheers

Gord

[RobinLegin]

Before you start tackling the water pump and touching the exhaust manifolds, do check the condition of the steel pipe tube and rubber hose that runs over the top of the V. It connects back into the heater matrix.
I had a constant little puddle between the V. All The cooling connections looked fine but further examination revealed the metal tube had corroded and however tight the jubilee clips, water seeped out and I was constantly topping up the expansion tank. All the pipe work and tubing was replaced with new. The V was dry thereafter.

[MandM]

Cleaned mine off with a paint scraper , and a bit of scotch-brite , checked the manifold sat ok with a bit of engineers blue, fitted payen gaskets from LD parts , with Stag wellseal and pushed the manifold down in the Vee while tighten the bolts. hope that helps, did mine a couple of weeks ago. but if you are going to remove the manifold you may as well rebuild the water pump, don't fit a new one.
I would not use Silicone sealer but that your choice.

Sorry about the spelling the spell checker is busy.

[Stevekid1]

I had similar problems with my Stag early on and also had to syphon out the excess water from the bottle and put it back in the rad. This was after I had replaced all hoses, steel tubes and had the water pump rebuilt. Although you have had the bottle pressure tested, when you have finished putting everything back together treat the bottle to a new pressure cap. That solved my problem and has been fine ever since.

Regards, Steve

[Phil S]

you should use a plastic or alloy scraper on ally heads

[richardthestag]

Morning Gord

A more common issue than it should be and possibly the reason for many a dead/overheated stag engine in it's day.

When the triumph v8 blows a head gasket the chances are that the oil will not be contaminated, so unlikely to see mayonnaise. You will however find combustion gases in the coolant, a simple block test will confirm this for you. as would removing the rad top plug, brimming it with coolant and starting the engine. a steady stream of bubbles is rarely great news.

The waterpump seals can leak, infrequent use of the car will just make that problem impossible to solve in the long term sadly.

Inlet manifold you really should make sure you use the correct gaskets with the water run off that stops coolant going into the inlet. BUT if your car has had thinner gaskets fitted then you will struggle to get the fatter ones to fit into the engine v without slackening one head off DO NOT DO THAT WITHOUT FITTING A NEW HEAD GASKET!

I clean old gaskets away with a stanley knife blade. yet to have an issue with that. with all gasket removed I would trial fit the inlet manifold back into the v without gaskets. it will sit lower but you should see that all faces of inlet and head are parallel with each other. If they are not? i.e. bigger gap at the bottom while the top of each branch is touching the head , you will be wasting your time.

Water pump gasket I have always fitted dry, follow the shimming exercise in the manual and you will not go wrong, unlikely that the water pump gasket will fail because of the structure of the cover. water pump leaks come past the seal and then leak into the v through an escape slot at the bottom edge of the raised section on the engine block. difficult to see but if you run a feeler gauge around the edge of the housing you will find it.

I do not like silicon as a gasket seal. to my mind it is just a messy bodge, I use blue hylomar or stag wellseal.

I also had a perpetual issue of the coolant not returning to the rad on short infrequent trips. but do 1000miles across Europe and it works beautifully. even the coolant leak into the v stopped.

As a result I fitted a HT, but then finding that the plumbing of it was a major cause for my hot running, converted it into a high level expansion tank with low coolant warning. So now the cooling system relies on gravity rather than vacuum to top the rad up on cooling down again.

Good luck with yours

Richard

[mole42]

Don’t use silicone. As often the case, Rimmers are wrong. As Richard and many others said, Wellseal is the stuff.
If you have the manifold off, check the bolt holes in the head, the threads might not be as good as new in which case Helicoils are your friend.
if you have a head gasket problem the top hose will become very firm as the system pressurises and is probably the first test you could do.

[ukbiggles]

Thanks to all who responded.

RobinLegin (Robin?), thanks for the suggestion on the metal pipe and hose across the head. Checked this and they both look in good condition so I don't think is the cause. The leak into the 'V' is definitely around the water pump cover area.

MandM and Phil, thanks for the suggestions on the scraper and Wellseal etc.

Steve, thanks for the tip on the pressure cap, had that tested when the expansion tank was tested. All seemed OK.

Richard, thanks for your comprehensive answer. In terms of the bubble test, I have several times had the radiator plug off when I refilled the system after a number of tests. No evidence of any bubbles after starting her up so I'm not convinced (yet!!) that it is a HGF problem. Current gaskets are the thick Payen type, and so are the replacements I have bought. Will use Wellseal instead of silicone based on everyone's opinion.

High level tank may be a solution, but I'll try the gasket replacement route first as see how that goes.

Thanks everyone for taking the time and trouble to respond.

Cheers

Gord

[Jeff]

Try some K seal first. It might just work. It won't cure serious problems but will seal small leaks.