Hiya
ABS engine Golf again.
Rattling sounds at idle from cylinders 3-4 end. Lumpy idle and inconsitant power delivery from the engine. Previous thread answers on this was to check for tappet problems.
Opened it up today and checked the cams. All shiney and look fine. Tappets don't move when pressed (lob's pointing up). So all ok?
A few oddities found:
1) possibly weak spark voltage from no1 plug (Plugs and HT leads, Disti rotor and cap are all fairly new) - measured on O'Scope with inductive probe.
2) Gunky crankcase breather tube - going to get that blown out
3) Compression test with a Laser test valve - only get 150psi per cylinder. However gauge seems to loose pressure gradually - whether on or off the engine? Odd.
4) When I turn the engine by hand you can hear air sucking at no1-2 cylinder end. Definatly from the head - not from the air intake
Grateful for any thoughts or advice!
Cheers,
James
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Best check the cam belt timing this sounds like the belt has jumped a couple of teeth. Regards Peter
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Thanks Peter - I hadn't thought of that.
J
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Peter, all,
Confused about the timing marks on this engine. Either its way out or i'm missing something. Cambelt was last done by VW - so I guess its the latter.
I've got the autodata and Haynes for this engine.
I've got the crankshaft OK - nice obvious notch there. The intermediate shaft (drives oil pump and dizzy?) seems to be unmarked. The dizzy is set to no1 lead and cylinder1 is at TDC.
They seem to disagree a bit at the camshaft it seem either to have to be at 11 or 12 o'clock. There seems to be no marks on the engine to align it up with.
Confused. Help?
James
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Right.
Found the marks. Confusing as somebody has tipex'd odd marks on the pullies....
The engine looks to be timed correctly. Crank and Cam line up and the dizzy is at plug1 position. Crank mark is at 12 o'clock and so is Cam.
Does it matter if the intermediate shaft is not where marked - but the dizzy is at plug1 mark?
James
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So more confused now.
Put it back together yesterday and started it up briefly this AM.
Rattle has gone and for the 20seconds I ran it it sounded smoother..... The only thing I could of possibly changed is the dizzy. It got removed and re-installed a few times. I didn't take the belt off.
Spark timing related?
I did wonder about taking the CAM off and clean the tappets - and try rotating the engine whilst all the valves are shut - aka it should be nearly impossible surely. See if the hissing is head or timing belt related.
Hmm.
James
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The cam and intermediate shaft sprockets have an indentation inline with the peak of a tooth. The cam lines up with the poiter at the bottom of the sprocket and if you temporarily replace the bottom pulley the intermediate sprocket mark will align with the TDC mark. If all is well then I would suspect you have a failed hydraulic cam follower probably exhaust valve. Regards Peter
Edited by Peter D on 01/02/2009 at 11:31
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Hi PeterD,
Now the weather has modderated a bit - or possibly i speak too soon...
I've taken the cam off and the tappets out for cleaning - they look absolutely fine - but i'll de-oil them and refit. Probably soak in some de-gunking fluid. (before washing out thoughly with new clean oil) The oil in them was old - aka dark.
As a test i rotated the engine with the cam off (so valves shut) - it still hisses - like pressure build up (aka cylinder rising) and then disappating (aka leaking).
Do I have problems with valve sealing I wonder?
I also wondered whether it was from the manifolds - but surely there is no pressure build up there to make the noise?
Grateful for your help so far!!
Cheers,
James
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Many years ago whilst driving in France I had a rattling sound come from the head of my Lotus/Ford twin cam head (fitted with L2 cams). On return to England I found it was caused by a slightly bent inlet valve.
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Check that all 4 culinders exibit the same resistance/pressure and hissing. When you have the cam back in do a compression test 7.5 bar ish when warm. Regards Peter
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thanks ggh & peterD,
Will do. 7.5bar is 108psi approx?
Cheers,
james
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Hi PeterD, ggh,
Right. I've cleaned the very stuck and gunky tappets. Re-filled with oil and refitted. Put new timing belt and tensioner on.
Had some fun with the timing... The first couple of times I started it - turns out the crank was perhaps 2 teeth out - and it ran sorta.
Sussed where I was going wrong and sorted it now. It now runs more smoothly but has developed a whole new noise. A high (higher than before) pitched ticking noise again from the head.
I wonder if i've bent a valve? Would just 2 teeth cause this?
Cheers,
James
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Oh - the compression has vastly improved. The engine is really hard to turn over by hand now... :-)
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Sorry - I meant one tooth I think. The difference to the crank with the pully on was about the same as 12 o'clock to 1 o'clock (say 30 degrees?)
Hmmm.
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I am sorry, I have never worked on your model of engine, so I do not know how close the piston gets to the valves. As PeterD advises, do a compression test. I would do the test with the throtle 1/4 or more open, both cold and hot so you can compare the results.
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Hi ggh1,
Sounds like a good plan. Waiting on bits from VW (waterpump, bolts etc) so when its back together I will.
Cheers,
James
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Hi PeterD, all,
Finally got the Golf back together after recieving parts. Its been running well all week and is much improved - both MPG (looks better so far!) and performance.
Compression tested it this afternoon and the hissing has gone! :-)
Cylinders are now reading (1-4) - 160, 165,155,155 all PSI. All plugs removed, full throttle and 5 revolutions.
Sounds ok? All within about 10%
James
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