Coolant leak

[DarkMatter]

Yesterday, all my troubles seemed so far away, I'd done a few jobs on the Griff, took it for a short run and put it away in the garage.

Today I got it out of the garage and spotted a small pool of coolant on the floor, approximately level with the back of the engine. I checked the swirl pot, no coolant, so added some more. Took the car for a short run and put it back in the garage, looked underneath and saw water dripping onto and off the exhaust flexi coupling

I had a good look around the engine and could see water beneath the plenum approximately above the rearmost nearside cylinder. It looks to me as though a gasket has sprung a leak - I'm wondering if this may be what I think is called the 'valley gasket' or does water flow through the plenum chamber?

Where could the water be leaking from?

Thanks, Andrew.

[spend]

No water in the valley gasket - only up heads, heater pipes go on top of the valley / under plenum, it might be those...

Dave
ETA: thats a bit ambiguous sorry... there is a water way on the heads at the rear, but pretty sure it is just blanked off by the valley gasket.. You don't want water in your sump...

Edited by spend on Wednesday 18th July 23:57

[V8 GRF]

Might be the unused Landrover temperature sensor on the top of the engine?

[AntonyJ]

Sounds very much like valley gasket, its exactly the same spot mine was dripping to(flexipipe on exhaust).

Valley gasket isnt a bad job to do, just time consuming.

[Hedgehopper]

On my car the thermostat gasket sprung a leak and the water dripped onto the metal valley cover. It must have been leaking for some time as the cover was quite rusty.

[GreenV8S]

There are lots of places in that area that can leak and drop water onto the valley gasket, where it will run back to the lowest point and run off. The valley gasket does seal the water passages at each end of the heads, but they're not weak points. My guess would be that the valley gasket itself is OK and you have got a plumbing leak in the area.

[DarkMatter]

Thanks for all of your suggestions. I've removed the plenum to get a better look. There are no obvious leaks from any hoses.

I've assumed that the metal casting which sits above the valley gasket is the inlet manifold and is secured to the heads by a number of bolts, anyway I can see a small pool of coolant near the bolt which is the second one in from the rear on the nearside, and more significantly the last bolt was only screwed halfway in and the rust on it showed it to have been like that for some time.

I've cleaned and refitted it and checked the tightness of the remaining bolts. Tonight I'll reassemble the plenum and run the engine to see if the leak has stopped, if it hasn't I'll have to look at the valley gasket.

What sealant is recommended for use when replacing the plenum? Am I right in thinking that Hylomar Blue is recommended for the valley gasket, and that a metal gasket is best?

Thanks again.

Andrew.

[GreenV8S]

DarkMatter said:

I can see a small pool of coolant near the bolt which is the second one in from the rear on the nearside, and more significantly the last bolt was only screwed halfway in and the rust on it showed it to have been like that for some time.

I think it's very likely you've found the source of the leak. Between the rear bolt and the one next to it is a water passage in the head blanked off by the inlet manifold. If the manifold is loose it's entirely likely that it will leak. I'd be concerned about how the bolts came to be loose though. It isn't a common problem for them to loosen themselves. It's worth torqueing them up and seeing if this stops the leak. If not you'll need to drain down, remove the intake manifold, you might need to replace the valley gasket but it may be OK, clean the mating surfaces and reassemble with Hylomar blue.

[DarkMatter]

Thanks Peter, good advice as always. I'm pleased to hear that the blanked off waterway is very close to where I've seen the pool of water. Let's hope I can get away without having to replace the gasket.

Andrew.

[AntonyJ]

DarkMatter said:

Thanks Peter, good advice as always. I'm pleased to hear that the blanked off waterway is very close to where I've seen the pool of water. Let's hope I can get away without having to replace the gasket.

Andrew.

Err for the small cost of the valley gasket , I would put a new one in anyway.
You have it stripped down this far......

[spend]

DarkMatter said:

Thanks Peter, good advice as always. I'm pleased to hear that the blanked off waterway is very close to where I've seen the pool of water. Let's hope I can get away without having to replace the gasket.

Andrew.

If it was mine, I would have been happier if it was coming from somewhere else.. Agree with Ant (you also want the end seals BTW), also you can have a 'free' cam check whilst your at it. More importantly make sure no coolant has been infiltrating into the slippery stuff. Its a great leap of faith that it would only leak on top of the valley gasket and not under it?

Dave

[DarkMatter]

Antony and Dave. Thanks for your suggestions, it does make good sense to change the valley gasket, but I was keen to get the car running for Brooklands today. Having refitted and tightened the bolts there have been no further signs of coolant leak - I can't be sure that's where the water came from, there's still a chance that it came from the blocked off tube which was tucked under the plenum chamber.
Andrew.

Edited by DarkMatter on Sunday 22 July 21:05