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V8 EFI coolant leak

Have just had cylinder head gaskets (in my 1988 Range Rover) replaced due to a gradually increasing loss of coolant. Apparently one of the head gaskets was admitting small amounts of coolant into one of the rearmost cylinders as the engine cooled. Great!

Not so great - The other day, quite soon after setting out, I noticed the unmistakable smell of boiling antifreeze. A hasty check revealed coolant dripping quite quickly off the rearmost edge of the nearside rocker cover onto the exhaust- at the junction of the cover and the rest of the engine (not the head I think) - Major panic and cautious curtailment of journey.

I'm taking the RR back to the mechanic who did the head gaskets etc tomorrow and thought that I would take another look before either gently driving it or getting relayed to him.

There is some, not a lot, coolant in the Vee under the Plenum. When I run the engine there is no coolant loss until the heat rises. Then I can see drips from the lower heater hose where it passes through the bulkhead - NB it is not necessarily leaking at the hose as I cannot reach it to 'wiggle it'. These drips diminish once the thermostat has opened.

Basically there are not sufficient drips IMHO to persuade relay man to take me to my mechanic on a flat bed :-(

Background over.

Now the questions: What is the circulation of coolant in the rocker/Plenum/Vee part of the engine? There's an awful lot of plumbing in that area, but I'm surprised that I can have lost quiet a lot of coolant (but not enough for the coolant warning light to illuminate) only once - i.e. I would expect there to be a hard fault i.e. split hose etc.

Any advice would be much appreciated.

TIA Richard

Reply to
Richard Savage
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Check the valley gasket. This sits between both cylinder banks and the inlet manifold and the coolant and inbound air run through it. It's a bit of a bugger to change, if only because of the sheer number of bolts you have to do and undo along with removing all the flexihoses/bowden cables/fuel lines/air filter/vacuum hoses. The gasket itself is quite cheap (I paid £18 for a coated metal one) and the actual fitting is technically simple, it's just time consuming.

What normally happens is that it starts pissing water out of the rear of the valley, just under the plenum (carbs in my case) so the water hits the bulkhead and from there the ground, possibly hitting the radiator hoses on the way down. If you're luck it'll hit an exhaust on the way out and you'll hear boiling water as a warning.

P.

Reply to
Paul S. Brown

Thanks Paul,

Sounds very much as if this is the fault. The anoying thing is that it was replaced at the same time as the head gaskets When you say 'check', how do you do this? (short of stripping all the plumbing off?). I don't think mine was too expensive, but it's black rubber.

I must say that this leak has found the only good use for the stupidly expensive exhaust manifold wrapping tape - the coolant soaked into the tape and then boiled.

BTW is it driveable (gently) - no reliance will be placed on your answer!

Cheers Richard

Reply to
Richard Savage

The canonical way is to have the engine bay steam cleaned and then dried and then dust the entire engine bay in talcum or kaolin powder, run the engine up to temperature, run it for a bot and then switch off and see where the damp is.

You will also quite often see coolant water in the slight gap at the back of the inlet manifold between the valley gasket rear seal and the rear of the manifold, but this may be different on an injection car.

What is probably worthwhile is getting somebody to check the torque levels on the manifold bolts and see that they are tight enough. Get them to do this by withdrawing and re-seating them otherwise you could just get the torque setting of a siezed bolt.

If any of these are under torqued then you could quite possibly get a leak caused. Be careful not to overtorque them though. You don't want to strip threads in the engine block.

P.

Reply to
Paul S. Brown

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