VR6 chain tensioner bolt removal/replacement

[Serial 0]

I recently rebuilt my VR6, all is going swimmingly except for a rather disconcerting chain noise from the right hand side of the head... During the rebuild I checked all the chains & tensioner pads etc, and found them all to be in good nick... but on reading more thoroughly through the forum I think I may have missed out priming the upper chain tensioner bolt properly. I basically just popped it back in and torqued it up. So... assuming this is the cause of the chain noise, I'm going to take the bolt out, prime it properly and pop it back in and see if this stops the noise. My question is... can I do this without removing the cam cover, or would that risk the chain slipping a notch and the timing going out?

[fla 9]

best bet is to remove the sparks and fuel pump relay and just crank the engine over for a few seconds. You'll hear a slight rattling whilst the tensioner bolt pressurises. Then refit everything.

[Serial 0]

OK so I took the cam cover off just to be sure that I didn't skip a tooth whilst the tensioner was out... got a brand new tensioner bolt, primed it with oil, fitted it, put everything back together and... the noise is still there. If I try really hard I can just about convince myself it's a little quieter, but it's definitely not gone...

 

Any other suggestions as to what I could try next? I'm thinking maybe insufficient oil pressure to the bolt, but not sure how to test for that (or cure it)

 

Also would it be possible that the oil I'm using is causing the problem? After the engine was run-in, I changed the oil for Silkolene PRO S 10W-50 Ester Synthetic Oil, which I think is slightly thinner than the recommended stuff... the chain noise seemed to start at about that time, and I also started getting loud oil-pump whine on cold starts after the oil change...

[fla 9]

i think 10W50 is slightly heavier than 10W40, and indeed this should have reduced any oil leakage/consumption. When i did the chains on mine it rattled for a few minutes as pressure in teh complete hydraulic system built up. Very disconcerting i can tell you but after about 1-1.5 minutes under no load (ie no sparks, hence no compression) this went.

Are your tappets ok and not worn? What is the mileage of the engine? And an aside - are you sure its coming from the engine and not elsewhere - metal will of course cause sound, any sound, to travel VERY quickly.

[Kevin Bacon 5]

I'm thinking maybe insufficient oil pressure to the bolt, but not sure how to test for that (or cure it)

 

Unlikely, unless you forgot to put the little O ring back in the chain cover plate, or accidentally pinched it. Have you got an oil pressure gauge?

What sort of noise is it? If the cam chain wasn't tensioned properly the mechanical slapping noise from the cams/tappets would be horrendous. A slight grinding noise after a rebuild is normal whilst the new pads and chains rub eachother, oo er. Mine was rebuilt 45k ago and even now I can still hear a little grinding if a listen closely, but the pad is mint still. A really loud noise from there is obviously not good. How loud are we talking?

 

Also would it be possible that the oil I'm using is causing the problem? After the engine was run-in, I changed the oil for Silkolene PRO S 10W-50 Ester Synthetic Oil, which I think is slightly thinner than the recommended stuff... the chain noise seemed to start at about that time, and I also started getting loud oil-pump whine on cold starts after the oil change...

 

Again, I've been using that oil for 45K with no problems and yep, the pump does whine a little from cold as it's thicker than the normal oil.

[Serial 0]

Are your tappets ok and not worn? What is the mileage of the engine? And an aside - are you sure its coming from the engine and not elsewhere - metal will of course cause sound, any sound, to travel VERY quickly.

 

I think the tappets are ok -- I had the head rebuilt by Impulse and I'm sure he'd have said if they were worn out... The chains have about 12000miles on them as far as I know, but looked absolutely fine when I put them back on during the rebuild... and its definitely coming from the passenger side of the engine, but not sure if its the top or underneath as I haven't had a chance to jack up and stick my head under whilst it's running...

 

How loud are we talking?

 

It's definitely a chain-ey sound, as far as I can tell from listening to various sound clips I found on tinterweb. It starts about 10-15secs after starting the engine, then gets gradually louder. Its loudest when the RPMs are dropping off, i.e. after a gentle throttle blip. It's loud enough to hear from the drivers seat with the doors/windows/bonnet closed. I took a couple of videos last night which I'll post up when I get home...

 

Thanks for all the advice, much appreciated :)

[Serial 0]

This is what it sounded like before I replaced the tensioner bolt with a new one:

[youtube:imxkwyg8]v9K5U2zV8Fg[/youtube:imxkwyg8]

 

...and this is what it sounded like afterwards... spot the difference?... I couldn't either... :scratch:

[youtube:imxkwyg8]AQGA00ZzUs4[/youtube:imxkwyg8]

[fla 9]

have you seen that oil is getting to the head ok?

[Serial 0]

Yes, plenty of oil in the head....

[Toad 0]

You are using the right tensioner bolt?

 

There are 2 types, one for the original tensioner, and one for the later one. Both need priming with oil before fitting/refitting.

[Serial 0]

I've got the 'early' one I think, it's got the little bump on the end with the hole that you poke a wire in to release the check valve. The tensioner pad has a groove in for the bump to sit in.

 

Took the car from Manchester to Colchester and back this weekend with no problems, however the chain noise is still there but possibly not quite as loud as with the old bolt... I'm not sure if it's a problem, although it does make me nervous, I keep having visions of bent valves and cracked pistons.... :pale:

[Toad 0]

Ok.

 

There is a seal inside which can go. Dunno if this is likely though?

[Roger Blassberg 0]

As above, you did put the rubber o-ring into the recess in the top cover, didn't you???? Otherwise the oil pressure might not pump up the piston in the tensioner bolt.

 

Best wishes

 

RB

[Serial 0]

I'm pretty certain I put the seal back, it was a small green O-ring if I remember correctly.

 

I'm gonna have one more go at priming the bolt, I'll leave it in oil overnight to make sure there's absolutely no air in it, then pre-tension it a bit by withdrawing the plunger a tiny bit more than I did last time and see if that fixes it... If that doesn't work I guess it's time to take the top cover off and have a look, I suppose it's possible something has snapped or come loose in the last 2k miles...

 

Thanks for all the help, much appreciated. :-)

 

T

[Toad 0]

You didn't put too much sealant on the casing and block the hole, did you?

[fla 9]

wouldnt that have cleared after a while though via oil pressure Toady?

[Toad 0]

wouldnt that have cleared after a while though via oil pressure Toady?

 

Depends how much there is I suppose. It's only a small hole so wouldn't take a lot of blocking.

[Serial 0]

OK, this evening I took off the upper chain cover. The small green O-ring was all present and correct, although there was a fair bit more sealant than I think should have been. I gave the oil gallery a good poke with a pipe cleaner and it's definitely clear. Couldn't see any sign of any broken chains/pads/guides.

 

However one thing I did notice, is the upper tensioner pad appears to rock slightly side-to-side on the pivot pin, is this normal? I could imagine that may make the rattling noise....

[Serial 0]

Bump... does anybody know if the upper chain tensioner pad should be slightly loose on it's pivot pin, i.e. it wobbles slightly from side to side...

[Roger Blassberg 0]

The upper tensioner blade moving slightly from side to side along its pivot should not cause a rattle.

 

Best wiashes

 

RB