BAG Engine loses timing after doing oil change - why?

[Crasher]

Did you remove and replace the righty loosie lefty tighty VVT hub bolt whilst locking the cams?

[willdudeuk]

Yep I locked the cams first then removed both cam sprockets......

Then put them back on finger tight with the chain so they were free to rotate on the camshaft.....then tensioned the chain....

Would a new bolt make all the difference? I bought all new bolts and seals last time......best practice would be to replace the bolts but I haven't done that....would it make much difference?


Not sure what I am doing wrong.....

Starting to think the chain is stretched.....but it was working fine before the oil change so a I am not sure that's the case.....(and like I said it was replaced this time last year)


I may get another FAI kit with chain and see if it makes a difference......


When the cams are locked there is still a little rotational movement about each camshaft but guess this is the pins rocking on the holes in the camshaft.....


What should I be doing next?

[Crasher]

Ahhh, FAI... I have had their chains stretch, how close together are the chains?

[

[willdudeuk]

Don’t think it’s that close. See the picture.

I bought another FAI kit and the chain is the same length from what I can tell....

I’m stumped. Not sure what I am doing wrong.


B42695D3-85D4-4CD1-8AFC-4724FB08BA8B.jpg

903269BE-91AF-4C59-8E41-FE77B9578164.jpg

new chain on left.

555D5183-D3C2-4177-872E-0E654B96CF59.jpg

[Crasher]

Are you using a crank blocking pin or a dial gauge through number 1 plug thread?

[willdudeuk]

The BAG engine from what i know doesn't have a crank blocking pin......only uses at DTI in cylinder 1 to set TDC....


Anyways.....I think I've clocked the problem.

I didn't set the DTI up correctly.


It bottoming out at TDC.....(the DTI only has so much travel....)

I reset the DTI when it was approaching TDC.....and by the looks of things.....timing is good....I can fit the T10171A tool nice and easily now with no problems....


I've literally spent the last hour checking the timing over and over.....

I don't like to go anti-clockwise if I've gone passed because I feel that slackens off the chain.....


Checked it over and over and looks to be good.


Won't know until I crank it over tomorrow.

Fingers crossed.

[willdudeuk]

Well it's back up and running.....

But it took an age to reach oil pressure.

Couldn't find the MVB in VCDS (not sure it has it.....searched in adv. measuring values.....)


Car ran horrible for a bit then once pressure had been reached it sorted itself out....(guessing the tensioner and guide putting pressure on the chain)

No codes for timing being out / correlation error so happy with that.


I guess the oil pump might be struggling / on way out hence why building a pressure head takes a while?

Think I will be purchasing an oil pump.....(OP332 FAI is the one I am looking at) if thats the right thing to do?


Just got 1 code I am not sure about.....




1 Fault Found:


19490 - Intake Air Temperature Sensor 2 (G299)
P3034 - 002 - Signal too Large


Readiness: 1110 0001

[Crasher]

The one I went through hell with I had used an FAI pump on and was sure it was the issue but a genuine one failed to make any difference... in the end I gave up and fitted a genuine VAG exchange engine. I am convinced the problem was with the timing chain cover but I could find nothing wrong, I am still mystified. The telling point was the genuine exchange engine was obviously a rebuilt head and probably a new block (no idea on the crank/rods obviously) but the chain cover was quite clearly brand new.

[willdudeuk]

So why do you think the timing cover / chain housing? What could cause the issue you were having?

I am still baffled by how long it took for the engine to gain oil pressure. The oil light on the dash did start coming on when I revived the engine initially.

It started off sounding bad / timing wrong after so many checks I was convinced it couldn’t be this so let the engine run to give it a chance for the new oil to circulate through all the galleries and enventually the chain tightened up and the timing was spot on.

Been out for a test drive and seems like it is sorted.

But we shall have to wait and see what happens on a cold morning when the oil is thicker....fingers crossed no jumping chain!

[Crasher]

I never did sort it, it was during lockdown V1.0 and everyone was furloughed or working from home, only myself in the workshops. After three patch up attempts to various depths, I gutted the engine down to a bare block which was acid dipped, decked (I found the deck had sunk in the middle, suggesting a previous major overheat) pressure tested and built back up with new pistons, all bearings, oil jets, genuine oil pump, brand new genuine head, cam carrier, exhaust cam, lifters, hydraulic elements, and a full Febi timing chain set. With it on the frame I span it over with a drill and got 3 Bar which is excellent for only 150 rpm or so. I put it back in but had to take the front pulley off to make room. When I was tightening it up (180Nm+180 degrees so f tight) one of the staff on Furlough paid a visit and came busting the through the door like a bull on speed and scared the **** out of me, I slipped... the timing jumped (he is due out of hospital soon). I stripped it all down again, new diamond washers for the fifth time and big bolt and started it up; to copy a phrase a friend of mine came up with, “it sounded like a skeleton ******* in a biscuit tin” and the oil pressure had collapsed... all I had done was take off the chain cover so I threw in the towel as I was already in for £20k in parts and labour and had quoted £5k! I ordered a new genuine engine which cam with a new chain cover which is theoretically a none wearing part and the only part I had not replaced or had re-engineered.