no compression

[steve12]

2.5tdi quattro been stood a while,just seemed one day had compression next it didn't.some people i've talked to seem to think its down to no oil in the hydraulic lifters can this be right.cheers

[Crasher]

Have you measured this lack of compression or are you judging this from the way it turns over and will not start? Does this problem come and go?

[steve12]

there permanantly you tell by the sound when turning it over off the ignition and when you turn over by hand theres no resistance all cams in one peice.can't work out how i've lost compression in all 6 pots.

[kenney]

Hi I don't think it is the hydraulic lifters,that are the fault.Have a look at the intake manifold flap.

[steve12]

are they easy to check over.thanks

[Crasher]

I could have sworn I mentioned the manifold flap sticking shut, where it go! Must have been another post! It is on the boost pipe coming up on the left of the engine bay.

I had a wide angle V6 behave like this a few weeks ago. It was a 2.4 5v but they are similar to the TDI. It came in on a flat bed and when I cranked it over and my first thought was, ohh bugger the cam belt has gone. The reason for the “bugger” rather the “cool” or some other expression of pleasure was that about nine months previously I had done the said belt. I ripped the covers off in a state of frustration only to see the belt was perfect and when cranked, all looked fine. The inlet tract was clear, the throttle opened, everything was fine and no codes, most odd. I got my chap Matt to crank it over whilst I watched and for him to keep cranking, it just span over as if there was no compression. I was just about to say stop when it went “cough” and then cough, cough cough, at which point Matt let go of the key. When he picked himself up after being smacked over the head with a breaker bar, we tried again. After about 30 seconds it stated to cough again and then one by one a cylinder kicked into life and then it took over from the starter and after about a minute all six were running. We shut it down and tried again, perfect. Left it for a few hours, perfect. Left it over night and still perfect. Over the weekend, still starting no problem and now a month or so later, it is still fine and back with the owner. The longest part of the job was putting the belt covers back on. All I can think is that it suffered an extreme case of hydraulic tappet jacking due to excessive oil pressure, something we see on older 4 cylinder TDI Golf 3’s quite a lot and occasionally the VR6, but these recover in minutes.

[steve12]

thanks i'll have a look asap hope its this could do without another bill on top of the injecter pump it already needs.thanks again

[Alan02]

2.5 5cyl. commercials do this too.spin over,non start.same fault with the pump.

[steve12]

can anyone describe abit better where this part is.i've already got the front of the car off ready to pull the injecter pump off but struggling to find this part.cheers

[kenney]

It is on the boost pipe coming up on the left of the engine bay.Why should you want to take the injector pump off??

[steve12]

Is it the flap on the left side of the main ally air intake pipesthat run in a u shape round the top of the engine and there is a flap just off left side front corner.should it be open or closed.cheers

[Crasher]

Yes, it should be open, it only closes for a moment on shut down to pull the engine down faster and reduce shut down shudder and unfortunately we are not allowed to post the pictures we have.

[steve12]

injecter pumps knackered,don't want to blow lump of moneyreplacing pump if i've got to replace engine.the flap described is in the open position.cheers

[steve12]

so if this flaps open and has been all along any other suggestions would be appreciated.cheers

[Crasher]

It sounds like tappet jacking. Do you have a diesel suitable compression tester? Remember that as this is done through the glow plug holes so that means removing the glow plugs. Firstly they can snap being removed and no way should they be re-fitted after the test.

[kenney]

Before doing anything else,maybe a stupid suggestion,anyway,check the timing belt to see if it is still in one piece.

[steve12]

timing belts in one peice,i'll get the pump done & refitted see what happens, then probably pull heads off & get them checked just bugging the **** out of me how you get all 6 pots going down at once.

[Crasher]

Two reasons spring to mind, valve hit and hydraulic lifter pump up. I would do a compression test before pulling the heads off.

[kenney]

How long has the vehicle been standing,is there any chance the exhaust system could be blocked??

[steve12]

don,t need compression test theres nothing there.it was turning over alright one day then went out to have a bit muck about with the next day and nothing.I first thought snapped belt,then maybe snapped camshaft,then has belts jumped tooth but all timed up,checked everything advised on here apart from the compression test.if i could find a complete motor i would just chuck a motor in it save scratching me head at this one.cheers