2000 Jetta low compression in 2 also limp mode.

2000 ALH 5 spd 124k

Bought it knowing runs rough, running on 3 cyl at idle when cold. 2 cyl has lowest compression. 450, 350, 410, 495. I just dropped 2k into rebuilding injection pump and injectors. From the guy in Portland. The pump and injectors were bad.

This car went through a dealership in 2016 or 1k miles ago for same problem and they through parts at it. Injectors, glow pugs etc. Then it sat.

The guy I bought it from did a head gasket new tb, wp etc about 6 months ago. But never got it running right.

Well here I am and it still doesn’t run right and boosts until it goes into limp. I shut off key and get boost back. BUT boostability doesn’t last.

I’m 4500 into this and need help.

The guy I bought it from gave me another ALH from a friend who wrecked his car. He was going to switch that motor in because he said it was a low mile motor that ran great till kid hit ice.

I have been reading the forum and was going to try to see if cleaning it out would bring compression back up. BUT I can’t keep boost going.

The shop said at this point may be valves or bottom end. I paid him and wanted to try cleaning it out but no luck without boost lasting.

Anyone have any advice. The shop is a reputable shop that works on VW and other German motors for 30 plus years here in Salem or. He knows what he is doing.

Any help would be greatly appreciated.

Oh the only code is misfire in 2.

No limp mode codes when it loses boost? What code specifically are you seeing?


//edit: This doesn't seem possible, are you using a real VCDS or a generic code reader?

Only code is the misfire code in 2. No code for overboost. VCDS. It was the shops VCDS. He took me for a drive to show me the code. His comment was I think it’s an overboost code for the misfire.

“The shop “ may know how to work on other VW’s......just not the diesels.....
Chances are you have two bent rods.
#2 is definitely bent..... #3 probably has a slight bend in it.

The only way to be certain is to pull the head and do a height check on all four pistons with a dial indicator at the point where the wrist pin is connected to the piston.....get several readings and average them.
Then use the Bentley and see what range you should be in , I’d probably use #4 As a guide.

This is fixable, you would need to pull the pan and pull the piston out, all four of them and send them out to be inspected.......personally I’d use the member on here by the name Franko6.
He will not steer you wrong and is a great resource and a great guy.

I used him on a project car that had a similar issues.......on that one the PO mechanic botched a TB job and it dropped a valve.......they brought the car back to him believing they had another problem and he passed off saying the head was bad......charged them but didn’t replace two bent rods and a beat to death piston......
That was my headache......

It’s either that or swap motors.......

Processing through this... I know cars, newer to diesel, about 3 yrs, could this be a turbo issue? It is not the 15. I think it’s the 17. But everything else is bone stock.

Long story short, the guy that fixed it that I bought it from said, a shop put a new japanese turbo on it. He himself put a used one on it. Wasn’t sure what though.

He is a diesel guy. Does great work. The head was pulled and pistons were equal. Turbo is a 15.

This is why I’m here.

Forget about the turbo.

If he does great work then there wouldn’t be a problem.

If you have a low cylinder compression then it’s either a bent rod, leaking valve, bad rings scored cylinder or a cracked piston.

If the head was off , what did it look like?

What are the numbers of the piston protrusion? How did he measure it , If just eyeballing it that’s not the correct way. A .020 difference makes a huge difference in compression numbers.

Agreed on the rods - probably had hydrolock from a failed turbo at some point. Cylinders 2 and 3 inject the most oil since it's a straight shot.

A used engine will be in the range of $300-$500 depending on what peripherals you want to keep with it. At this point, it would probably be your best bet on reducing the time to resolve and how much more $$ you can sink into this project before you just bury it whole.

Good luck,

PH

You need to pull the head off and check those pistons/rods. You may have to actually remove them from the block to get a good measurement on them.

If the guy "did great work", then the engine would be running great. It isn't. That is why you are here.

Also a possibility something is amiss with the head, too, but usually uneven/low compression numbers are a result of something in the lower end.

There is a fixture that machine shops will use to accurately measure a connecting rod's length and trueness. And of course the piston rings, piston ring lands in the piston, as well as the condition of the cylinder walls themselves are also only able to be fully evaluated with the pistons/rods removed from the block.

VAG engines are manufactured to VERY exact standards, so any difference in these things such as rod length pretty much guarantee there was a hydrolock situation at some point.

Copy that new motor it is. Thanks.

Update, turbo is sticking. Stupid thing runs good now except for turbo. Haven’t switched motor yet, but now I need to get turbo running good.

Murlen1976 said:

Update, turbo is sticking. Stupid thing runs good now except for turbo. Haven’t switched motor yet, but now I need to get turbo running good.

Click to expand...

I would take the actuator off the turbo first.
It's only 2 nuts, the vacuum hose, and a clip.
There's a VW bulletin about the actuator rusting internally.
You can turn it over and rust may come out.

While it's out work the arm that the actuator moves back & forth full range.
It should move full range smoothly, easily, and not sticking.

If it sticks you may be able to work the arm back & forth for a while to loosen it up.
Others have opened it up to clean it.
Search for cleaning the turbo here, many good write ups.