Help! A4 3.0 TDi ASB No compression after head work and new timing chains

[Lang]

Hi Guys, 

Newbie here , bit long winded so please bear with me 👍

I bought a 2007 A4 3.0 tdi with a snapped cam chain on the left side (cyl 4-6). 

I removed the head to find no valves were bent but seats/guides were worn so gave head to cleasbys in Durham. Got head back with 12 new guides and 6 new exhaust valves. 

Head refitted with all new genuine Audi head gasket, bolts, all 4 new genuine timing chains, guides and tensioners. 

Bought a set of timing pins for this ASB engine and I have access to a genuine Audi workshop manual. 

Everything timed up but when I crank the engine over by hand there's no compression in cylinders 4-6, the side I had the head off! I have compression on cylinders 1-3. 

With the cams removed I have compression on 4-6.

I started doubting the exhaust camshaft, wondering if the lobes had moved when the original chain snapped (thinking that was why no bent valves) so purchased a 2nd hand one. I didn't actually fit it cos the camshaft was scrap so sent it back. However I put them side by side and the cam lobes looked in identical positions.

My next theory was the camshaft timing. I'd only painted my own timing marks on the cams before removing them so I decided to buy the Jig required to time the cams up (£600!) to be 100% sure, and yep, my cam timing is spot on but still no compression. 

Has anyone any idea why I'm having so much hassle? Something I'm overlooking or something I'm not doing correctly? 

Started even wondering if the new valves are the correct spec/size!!

Be grateful if someone can put me out of my misery 😀

Thanks in advance for taking the time to read this and for any help.

[Trevor]

Hi Paul...welcome to the forum

Sorry to hear you've had a nightmare of a time so far.

I would check the rear of the cams (if fitted with gears to synch the cams) as did a similar job on an Alfa recently and found the gears were out of phase as had moved on the cams with having keyless pulleys when the pistons hit the valves, took me a while to suss that one out....just a thought!

Also, if fitted with hydraulic lifters, maybe empty them out before fitting. Alternatively, you may be right about the height of the valves being incorrect

Let us know how you get on with it

Cheers   Trevor

[Lang]

Hi Trevor. 

 

Thanks for the reply. 

I've just been and bought a new genuine exhaust camshaft today so hopefully will get to fit this at the weekend sometime.

If I still have issues I can only presume that incorrect valves have been fitted. 

The hydraulic lifters are empty of oil and can be easily compressed by hand so doubt they can be to be at fault. 

Will keep you updated how I get on. 

 

Cheers. 

[Lang]

Update.....

New camshaft fitted but still exactly the same!! 

Hate this car. 

[Trevor]

where area are you going to be looking at next?

 

[Lang]

It can't be the inlet camshaft as the lobes can't possibly move so my only other theory is the incorrect exhaust valves. 

Debating whether to measure the valves in the right side head and compare the valves that way. Don't really want to remove the head again unless 100% certain the valves are wrong spec. 

[Trevor]

That would be really annoying if it was the valves as head off job to replace them.

You should be able to measure the height of the valves compared to the other side (in the closed position) to quickly determine if they are wrong.