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I'm Forever Blowing Bubbles :-(


Ben Powers
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A bit more advice from the RHOCaR bods please. Having just completed a very fun 2x1minutes driving at a sunny autotest I had water blasting out of the cap on my water bottle. Revving the engine produces bubbles in said water. The general consensus is that the head gasket has gone, there is water weeping from the inlet manifold too.

 

Its a Rover V8, still running ok, limped the 5 miles home in 5th at 30mph without issue and water temp reading normal. I'm a newbie mechanic. How serious is this problem?

 

Something I can take to a garage (any recommendations in the Kettering area?) (what sort of price should I expect?)

 

Something I can fix at home in a very basically equipped garage?

 

Time to sell the car to someone more handy?

 

As ever, all help gratefully received.

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If the head gasket has gone, an easy check is see if you have a whiteish emulsion on the filler cap or dip stick, this is caused by oil & water mixing. The engine would probably be lumpy, belching white smoke and generally very poorly usually.

 

If there is water leaking from the inlet manifold, this may be your problem and should be easily fixable (damn sight easier than a head gasket, as with a V8 you have 2!!)

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:-D Excellent. The water is clear, even when in 'jacuzzi mode' there is no sign of oil in the water, likewise the oil on the dipstick is clean. And the engine runs normally (not technically the same as smoothly!).

 

So inlet manifold fixing. Dare I ask, is it a case of bolts off, replace gasket, bolts on?

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could be a head gasket, but you say its not running badly?

 

whilst some of the tests advised above are an indicator, they do not prove or disprove a head gasket failure.

 

if a gasket fails between a coolant gallery and a cylinder, oil and water are unlikely to mix at all, it is more likely the engine will run with a misfire but not guaranteed, and may produce white smoke.

 

a failure between oil gallery and a cylinder is unlikely to cause overheating, and certainly no bubble in the header tank, but as above the engine may or may not run normally and may produce blue smoke.

 

It is possible for the gasket to fail between oil and water galleries, the two will mix, but the engine will perform normally, but may overheat in extreme conditions.

 

the white "sludge" is common on some engine, caused by condensation in the crankcase, a by product of cars used for short journeys.

 

I have done head gasket replacement on those engine, when they were in 31/2, P6 and SD1, and being alloy they can be difficult to diagnose with any certainty. You just have to look at the evidence, listener to the description of the fault and make your best judgement.

 

There is one fairly sure fire way of diagnosing a head gasket failure. A chemical test of the gasses in the cooling system, if exhaust gasses are present the liquid changes colour. A lot of garages have this equipment, its cheap and takes approx 5 minutes to get a result from start to finish.

 

http://www.importtuner.com/tech/impp_1108_blown_head_gasket_diagnostic/

 

I would find a friendly tech with the equipment, a few quid will confirm the diagnosis, may still need doing but at least you can say with certainty.

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Absolutely agree with KT. An extra test that might help is a leakdown test. Each cylinder is pressurised in turn by compressed air through an adapter in the spark plug hole. A single cylinder may show a more rapid pressure drop than the others and I once could hear air bubbling into the coolant and see the water level rise in the rad. (It was a big leak!)

 

Nigel

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Guest Tim Norman

What fuel system and cooling system are you running. My first attempt had a self perpetuating air lock!

A little redesign and it ran as sweet as a nut and never overheated again.

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Guest peter2b2002

first check compression on each pot, bubles showing when hot or all the time? 3.5 or 3.9 ? i,ve done head gaskits a few times on my range rovers over the years not a hard job to do, the valey (inlet manifold) gaskit can be a bit tricky but be careful torquing down the heads also check the water pump on some of the old 3.9 had dodgy liners prone to go porus, good thing about v8 they are tough as old boots

peter2b

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Thanks very much guys. I think, given the weeping at the inlet manifold that I'll have to replace that anyway, whether or not its the real problem. I should be able to get on that this week, having a nosey around it last night it does appear to be within my trainee spanner operator skills. Pictures to follow in due course. It would be really helpful if someone could point me in the direction of the right gasket once I do have some photos up. I'm clueless as to what is actually in there except for a 3.5l RV8 with carbs (offenhauser or something like that?). I really am a n00b at this stuff!

 

If that doesn't fix the problem then its off to my local friendly back street garage for greasy overalled old boys to work on. I'd rather have it done properly than risk me buggering it all up for the sake of a few pounds.

 

The good news is that I'm sure the engine didn't overheat at all. The temp guage never went above 90, I appreciate if there is no water in there the gauge is useless but I'd have thought if that were the case it would read lower. The 5th gear crawl home was about 60 and engine operated normally. There was still water in the header tank when I got home.

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I think this could be a case of inadequate cooling at low speed. Autotesting needs a massive electric fan to cope as you'll have no ram air effect.

This compounded with a water leak and you'll soon have air in the system. It's this air that expands and causes the excess pressure resulting in the cap venting.

Sort the leak, make sure its definitely not got any air locks by having the header tank higher than the top hose when filling the system and go for a run at decent road speeds. If you then have no issues go back to my original idea of it being an unsuitable electric fan.

 

The RV8 is susceptible to inlet leaks where the water ways pass from head to inlet especially if it has the cheap and nasty tin valley gasket that rust.

 

HTH,

 

Nick.

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Hi,

If you do have to replace the inlet gasket I would go for the composite one as the tin ones are liable to rust as was said earlier. It is a fairly easy job, but like many others worth taking a bit of time over esp cleaning off all the old gasket sealant and getting all the torque settings bang on. If the engine still uses the little rubber gaskets (use new ones) and clamps at the end of the main gasket then make sure these are correctly located before you tighten anything down. It is a few years since I've done one so there may have been some improvements since then! Even head gaskets on this engine are easy enough for a novice ( I was ) just time consuming. As has already been said if you can find out exactly what the problem is with the exhaust gas test then you will now where you stand, you don't want to replace the manifold gasket and then find out you have to do a head gasket. Best get it all over in one hit. And don't drop anything down any of the galleries like I did with a dodge V8!

 

Regards

Kevin

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  • 3 weeks later...

So. Despite some set backs, like putting all the head bolts in and noticing the alternator bolt had to go in first, then then repeating the process and realising I'd forgotten the sodding gasket, and then repeating it and realising I;d forgotten the exhaust gaskets etc etc. It now lives :-)

 

BUT. I do definitely have an airlock in the system. The pipe running from the inlet manifold to the top of the radiator can only run at the height of the top of the filler resorvoir. How on earth do I eliminate this? Now its running its going straight on ebay, sadly, but I want to get it properly sorted so I can sell it in good conscience. I've tried topping it up and driving and topping up and driving but the temp gauge still sits on the minimum stop. I've tried massaging the offending pipe and it gurgles but doesn't fill with water. I've tried swivelling it round so as to run as low as possible but the thermostat housing means it must leave the inlet manifold in an upwards direction. :-/

 

Anything obvious I'm missing?

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I assume your filling it through the top of the rad? If so get the engine upto temp so the stat is open and jack the front of the car up as high as you can and keep filling with coolant.

I used to have to get the back of my Bowler about 4' high to fill the coolant without air locks due to the rad being in the back.

HTH,

 

Nick

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