BAG Engine loses timing after doing oil change - why?

[willdudeuk]

I’ve just done a service on my 1.6 FSI BAG engine code and the timing has slipped slightly as it is sounding rough as anything....

Why is this happening?

I never had a problem before.

Any help would be appreciated.

Thanks

[Crasher]

The tensioner is a stupid design, unlike most hydraulic tensioners it has no anti return spring so after an oil change the chain is very slack until oil pressure builds up and if the chain is worn, the cams can easily jump, the 1.2 3 cylinder 12v is notorious for jumping after an oil change. It is such a **** design that I have even known them jump when doing a clutch when the mechanic moves the engine anticlockwise and on one occasion I had a customer with one jump as he left it in gear with the usual failed Golf 5 handbrake and the car crept backwards and jumped the chain. That it is not your fault is no solace knowing you have to rebuild it but when we do oil changes on any chain cam engine we take the plugs out and spin it up on the starter to get oil pressure without any compression pulses. How much would it have cost VW to machine a ratchet and fit a simple leaf spring to the tensioner like the larger EA888 engines have? Mind you, they also jump because the tensioner design was crap even though it has a ratchet!

[willdudeuk]

Thanks Crasher I’ve got is stripped down ready to be rebuilt.

Looks like the exhaust cam was ever so slightly out....(not sure if advanced or retarded).

It was making quite a racket when I turned it over after doing the oil change (stupidly I didn’t do what you have advised - plugs out until pressure has built up).

Weirdly enough I didn’t get any low oil pressure light on dashboard?

Also noted that when I removed the oil filter housing on top it was bone dry???

I almost suspecting that the oil pump chain may have failed? Or oil pump has gone?

Haven’t got the control housing off yet to see but will update in due course.


FYI the chain was replaced last year. The previous chain was stretched and compared with the new vs old it was quite a few mm longer!



So going forward when doing an oil change always remove plugs to build up pressure.


If you have any further advice please let me know. Appreciate it. Thanks.

[willdudeuk]

Built it back up but the timing isn’t right.....

Sounds horrible so quickly shut it down.

I get checking the timing again and again....

It seems the laser 5742 locking kit I’ve got isn’t doing it’s job....

I must be doing something wrong.

After getting the timing right with the locking tool the chain is nice and tight but when it is removed it goes really slack....valve springs are causing it to rotate out of position and lose the timing....

Not sure what to do so any help would be appreciated.

[Crasher]

In bought that cam to cam lock years ago and it was awful, nearly impossible to use so I bought the genuine VAG version

https://hosting.photobucket.com/albums/dd20/Crasher1964/.highres/P1010010_zps225654c8.jpg (https://app.photobucket.com/u/Crasher1964/p/009ad632-4a4d-48b3-8f5e-00985346b43e)

[willdudeuk]

Any chance I could borrow it? I am seriously struggling......

I managed somehow to do it last time.....


I took the chain off to double check it wasn't stretched....... compared it to the old stretched one and was at least 5mm shorter in length when hung up against each other....


Starting to think I need a new motor.....

I am open to suggestions please (has to be minimum Euro 4 Petrol or Euro 6 Diesel so I can drive my car in city centre....Birmingham has the CAZ clean air zone coming 1st June....)

[Crasher]

Unfortunately we don't lend tools, I was going to suggest that being as they are only £50+VAT that you buy one from a local TPS but there is no UK stock. Also from what you are saying I think the problem is deeper than the valve timing. I want through a living hell at the end of last year/beginning of this year with one of these engines in the 1.5 twin charger format, I had such a nightmare with it in the end I fitted a brand new genuine VAG exchange engine but with your car that is no longer an option as these have been obsolete from VW since 2019.

[willdudeuk]

Yer I’ve looked at it again....

Thought perhaps if I rotated past the sprung point and rotated back it would put more tension on the chain...ie rotate exhaust cam clockwise and intake can anti-clockwise. Then rotate back and engage the T10171A tool....but it was reaching the point where it would spring back to the original position

But that didn’t work.....

I can get the exhaust cam to line up but the intake / VVT cam I cant.

The chain seems too slack when there is no tension from the tensioner....but think that is by design?

When the chain is tensioned it causes the intake cam to rotate anti-clockwise and almost bring it back into correct timing....

Can’t understand why I can’t get it set right.

Could the valve train be damaged?

Chain stretched?

No oil pressure?

Oil pump not working? Pickup pipe blocked?

[Crasher]

Did you replace the VVT hub?

[willdudeuk]

Yep VVT is new.....(well replaced last year - when i did the whole timing chain kit etc....)

37842

Timing chain must remain remain tensioned on both sides......



Also from what you are saying I think the problem is deeper than the valve timing.

What else could it be? Thank you

Been following the workshop manual to the letter......

I've only got the BLF version but I understand it to be the same process....

[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?

[https://live.staticflickr.com/65535/51052616231_d24e335797_o.jpg (https://flic.kr/p/2kMm1ae)

[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.


37843

37844

new chain on left.

37845

[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.

https://live.staticflickr.com/65535/50251558803_90e0f92d3d_o.jpg (https://flic.kr/p/2jyynGg)