look liek normal machining marks to me. however I notice all the pistons are at the same height, your crank is buggered
I'm surprised you've had problems without putting the engine under load, but maybe a metal gasket needs a harder squeeze? Do you trust the torque wrench that you tightened them with? When tightening head bolts or studs, I always overcheck them all, once I've tightened them to the specific torque (before the 2x90 degree turns, if they're vw type stretch bolts), because there's a settling effect as you tighten all the bolts, and the first ones could be slightly slacker than the last ones to be tightened. Don't know if you did this, but I wouldn't have expected differences as big as you're seeing.
Well this problem only seemed to appear once I properly started giving the car some beans. When I say 'beans', I mean up to about 4000 rpm and up to about 150kPa (1.5 bar) absolute pressure. Not much, but more than what the engine had seen previously. Ever since building the engine it had been used very gently; then on one weekend I started pushing it much harder. Then I left the car pulled up over a week and the weekend following I suddenly realised it was producing all this steam. It's at this point that I used the Block Tester and discovered the positive reading. I have used the Block Tester on this car many months ago and it stayed dark blue. I sort of trust the torque wrench... I do have a normal Halfords mechanical one that I'll check with also.
Definately looks to be more 'dense' steam produced from coolant rather than thinner condensation Have you tried a leak down test Trev? That would give you a definate yes/no on the possible (likely unfortunately) head gasket problem. I know the tester seems conclusive, but a leak down test would give you an obvious visual indication (bubbling) in the expansion tank wouldn't it? Neil.
I've never done a proper leakdown test. I've just quickly read up about it and I understand that you put the piston at TDC and then you use a threaded adapter to feed compressed air into the cylinder, yeah? And then you go around seeing where air is coming out (e.g. bubbling in the header tank as you say) - is that how it works? I wonder if the tool / adapter can be picked up from somewhere tomorrow because I'd like to give this a go.
Yep, thats the idea Trev Not sure on the adapter, but id say most 'good' garages will have one...A mate of mine does anyway. Would be good if you can get it to a garage who would give it a check for a few quid. Neil.
A kit on ebay But id see if you can have a garage do it for a few quid if you can as its a bit pricey. I guess the end of a compression tester gauge could be modified/piped up to hook up to an air line. You would have to remove the 1 way pin/valve bit and meter the amount of air carefully. Neil. Edit:Ahhh, it says in the auction that the ends are available seperately
I'm impatient and want to try this leak down test suggestion tomorrow, so I think I'll buy a second Gunson compression tester from Halfords, and do this simple DIY idea: http://www.max-boost.co.uk/max-boost/images/Leakdown_tester/leakdown_tester4.jpg
Cool, kinda what i was thinking along the lines of. I think ill keep hold of my broken Gunson compression tester come to think of it Let us know how you get on Trev I wouldn't go mad with pressure if you don't have too Remember to remove the expansion tank cap also! Neil.
Yeah - I finally now have a use for my broken old tyre airpump - the bit that I'd be chopping off is buggered.
By the way, at the moment the coolant never seems to become pressurised in the way you'd expect when you have a head gasket failure. When I let the engine really warm up I may see the level in the coolant tank go up by 1cm or so, but you'd expect that anyway wouldn't you. But I don't see the coolant bubbling or trying to escape out of the top! I suppose it's possible for a leak to be so small that you'd never see it affecting the header tank under normal operation; you have to do a leak down test to see it. Presumably the header tank boiling over means a major failure.
Today I made a leak down tester using the DIY method above. I used it when the engine was cold and I think that air was getting past the rings as the pressure would gradually drop within seconds, so I had to keep pumping air in. Did so at about 4 bar (the maximum pressure I could get away with, while still being able to lock the engine to stop the piston moving). Could see absolutely no bubbles in the header tank whatosever for any cylinder. I guess it should be done when hot really but I already have the manifold and rocker cover off and I was hoping to see a 'before' and 'after' once I had re-torqued the ARPs. Anyway I'll torque them all up in the morning and re-assemble everything and see how it runs. If the Block Tester still goes yellow then I'll do the trick of pulling out each HT lead in sequence and try to isolate the cylinder leak that way. Trev
Aye, definately would have been better if warm...lets any cracks/splits expand which im sure you already know Trev. Not sure what else to suggest at the minute (Im on the budweisers) Has the head been worked/ported at all? I wonder if you could have a hair line crack somewhere which is pulling coolant in through a port, and contaminating the coolant? If it was a crack in the head somewhere then the leak down test you did wouldn't show it up. Im not entirely sure how possible that scenario is tbh...Just throwing an idea out there Was going to ask about charge cooling (air-water etc) but that wouldn't contaminate the coolant.
Hmm... The head has been worked on, yes. Not a totally pro job, though: First of all, it had a bit of a 'DIY' port job by the guy I bought it off years ago. Then, when I got the machine shop to rebuild it with new valve guides and stuff, I got them to tidy up the porting for me. If I end up taking the head off then I do have another rebuilt head that I could consider wanging on instead.
I think Riley + buds has sussed this out. Exhaust port to coolant channel 'short' would explain all observed behaviours, I think.
Sorted, ive got to that really drunk.sober stage now...Who wants to know the meaning of life? Or maybe im so drunk i can fix my 4 year problem on the G60! Good luck with itTrev.
Just applied 80 ft lbs all round and rechecked three times. Put it all back together and run it again. Now I've run it without the coolant expansion tank cap on, and I see that it is starting to expand and escape out of the top even when the temperature gauge is only just starting to creep up. I admit that the level was already a cm or two above 'max' though. Also, I've seen a few bubbles. Not very many, but a few. What would you guys describe as normal? If you're watching the coolant while the temperature rises from cold, would you expect any bubbles at all? I think now I'll pull HT leads in sequence and try to isolate the yellow fluid to a particular cylinder.
