MG ZR Forums banner

1 - 4 of 4 Posts

·
Registered
Joined
·
309 Posts
Discussion Starter #1
hi all. My car has been losing coolant recently and was just about to go in to get a new inlet manifold gasket fitted. The garage said it may in fact be HGF but the HG was done three years ago with the MLS gasket and there haven’t been any other signs of HGF (heaters give heat, no may etc). There has been white smoke on starting.
Last week it suddenly dumped its coolant everywhere - it turned out there was a hole in the hose caused by rubbing against something hot. The RAC fixed it, filled it with water and got me home. It drove well enough, but now suddenly cuts out very soon after starting.
If it’s just inlet manifold issues, could water have got into the plugs/pistons to cause this? (It hasn’t been driven for a few days, so may have built up)? Or is it likely to be something worse??
 

·
Registered
Joined
·
1,363 Posts
You mentioned that you had been suffering 'white smoke' at start-up. Whilst some vapour from the exhaust whilst the engine warms up is normal and nothing to worry about, if the vapour is excessive it does suggest the prescence of moisture in one or more cylinders which burns off when you start the engine (with the exhaust vapour rapidly reducing).

The most likely source of moisture in a cylinder is from a leaky inlet manifold gasket - depending which end of the manifold gasket is leaking, it will be either cylinder 1 or cylinder 4. I would have the spark plugs out to start with and see if either of the plugs for those two cylinders look cleaner than the others as this would tend to support the idea.

IMG is relatively easy to replace (although the lower nuts are a bit inaccessible) and if doing so I would recommend only using one of the newer type black viton gaskets (part number LKJ101110) which are a bit thicker and more robust than the standard green gaskets, and are not all that expensive now. Avoid the very cheap aftermarket green ones.

I wouldn't rule out the head gasket altogether though - repeat failures do happen unpleasantly frequently, and whilst an IMG leak would cause a misfire for a short time after starting, it would quickly clear as the cylinder dried out, so I think something else is causing the engine to stop (though perhaps still not HGF).

HGF may not cause emulsified oil in the coolant or oil filler cap - it may fail at the fire rings which would allow exhaust gases to get into the coolant and coolant may seep into the cylinders when the engine is cold. Exhaust leakage into the coolant can often leave the coolant system with significant residual pressure in it, even when it has cooled right down, and this can help push coolant into the cylinders. A 'sniff test' on the expansion tank using a gas analyser (such as used for emissions testing) would confirm if there are excessive gases in the coolant.
 

·
Registered
Joined
·
309 Posts
Discussion Starter #3
Thanks for that. Yeah I suspect that a little water in the pistons was easily burned off, but not driving it for three or four days allowed more to accumulate, so trouble. I***8217;m told it could be a hydraulic lock, which would be bad news :( As would HGF. It***8217;s done a lot of miles and has been a terrific car. I***8217;ll try and get it going again if I can, but will prepare for the worst.
 

·
Registered
Joined
·
309 Posts
Discussion Starter #4
Managed to turn it over with the plugs out and a nice jet of coolant came flying out of cylinder 3. Not a torrent so may have escaped engine damage. Next step is to put the plugs back in and see if it will start
 
1 - 4 of 4 Posts
Top