ALH newbie needs help / advice

regarding compression: VW specification is 360 to 450 psi new. At 1/4 million miles of obvious less-than-ideal maintenance I don't think that 10% under new minimum is too bad. VW specification for maximum difference is 70 psi. I'm at 15. I have other worries.

It revs up just fine with no intake or exhaust manifold. I began bolting things back on the head. The exhaust manifold and turbo were attached and plumbed to the oil supply and drain. The hot side outlet (down pipe) and the cold side inlet and outlet ports are still open. It revs up to redline.
I added the intake manifold, the EGR cooler, the EGR valve, and connected the piping between these. I did not connect the vacuum operator line. The low limit rpm condition returned.
I know.....I said one-by-one but then I did three at once. Tomorrow I'll take off the EGR items and try with just the exhaust manifold and turbo, and the bare intake, and go from there, one-by-one.
No really, this time I mean it.

Interesting problem. Mouse nest in the intake manifold!

Ham sandwich jammed in aftercooler?

Wish I was there to poke at this thing. Interesting!!

So... Ex mfd, turbo, downpipe on. Coldside scroll on, but no intake mfd. Revs ok.

Intake clean, installed, egr and other air piping on, problem returns.

Ham sandwich in aftercooler. Bingo!!

On a serious note, start from compressor outlet and go step by step through the flowpath to head.

I'm still wondering about intake ports and valves in head, where valves were not pulled when head was off..

And does turbo spool well? As in lots of air moving through cold side scroll when piping off and engine running? A sticky turbo will cause your trouble and air flow at idle will be minimal as a symptom..

The intake manifold is apparently the culprit, why and how I don't know.
The ports in the manifold are open. I can push a cloth rag through each of the ports and out the air inlet port so it's not like the manifold is blocked. The gasket lines up with the manifold, the gasket lines up with the head, so I have to presume the manifold lines up with the head.
No intake? Red-line!
Intake (no anti-shudder, no EGR) bolted on? 1800 rpm max!
I've identified WHAT is the problem. Now to identify WHY is the problem.

Curiouser and curiouser...

I have a spare manifold known to be good I can loan you if you want to try a different manifold. LMK.

Try it with out the gasket just for the sake of it, I'm really curious about this one. Also can you push the cloth back through from the intake end and out through the ports? I'm thinking if there's something that gets pushed flat when you put the cloth one way but might be sticking up and blocking the manifold when air is trying to go the other way. Sort of like a piece of paper would do if you held it down at one end then blew it, the end would lift up? Just a thought but it's the best I've got on this wierd one.

If you connect the intake up to a shop vac is there a big change in the shop vac's pitch?

-J

I have seen people clean the manifold before with just hand tools and have similar (though not so severe) issues. There were still choked areas deep inside.

Soaking with diesel fuel and bioD for a week or two, then burning out redneck fashion, or cleaning with a high pressure wand, then spinning a frayed out 3/8" cable in a drill(frayed and bent out large enough to scour all sides of each opening at once as it goes in) told the tale. I run the cable CW and CCW back and forth in each opening and out each opening (all the way through), even in port #1 and out port #4 and vi ce versa. When this produces no more bits or dust, then I am fairly certain it is clean.

I've got an extra intake manifold if you want to try.

Stupid idea, maybe you already did it - put the intake manifold on without the gasket.

upside down gasket? ;-)

I've discovered there was (is) a fair amount of build-up in the 'front' wall of the intake manifold body. Not so much that it should have been an issue, but it apparently was (is).
Right now I have the manifold in a dishpan, the inlet port blocked by a racquet ball I stole from Sassy's toy box, and the manifold filled with degreaser. I'll let it soak until Saturday and see how much more I can get out of it.
I connected the downpipe, blocked the EGR port and revved the engine to red line several times.
It looked like Mt. Pinatubo erupting with all the soot being blown free of the exhaust. There was a good 20 foot circle of black dust all around the back of the car except for directly under the tailpipe outlets. It looked so pretty when the slightest breeze would create swirls and eddys and the fine particles were moved.

You should get the takeoff after re-assembly on video. I bet the exhaust is quite constricted with buildup.

-J

Yeah - I'll drive up and video tape that.

Jettascuba said:

upside down gasket? ;-)

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Done that more than once....

Mouse nest in the manifold for the win!

I feel bad for the poor cat! now its clogged too!

Liseed said:

Mouse nest in the manifold for the win!

I feel bad for the poor cat! now its clogged too!

Click to expand...

Stop feeding it cheese

Third time's the charm.

Now that the intake has been cleaned for the third time (4th counting the prior owner) the engine revs up to red line with everything on and connected.

I had removed and cleaned the manifold when I first began this ordeal (post #1). It wasn't all that bad. I've had others that were visibly much more restricted, yet ran up to speed without issue. I cleaned it anyway.
I bottle brushed through the manifold the second time (post #14), with no improvement. "Flossing" with a rag also indicated that it was open.
Soaking the intake manifold in degreaser for 36 hours appears to have removed whatever was the problem.

I wonder if just one runner was clogged and the ECU tried to balance things out by lowering power. Interesting exercise in troubleshooting.

I'm glad you located the problem, I respect your diligence at locating the problem. I cleaned my manifold when I first bought my TDI. You have added more information to my library of possible problems and solutions

Final update to this thread. I had full RPM range but so little torque (power) that it still barely got out of it's own way. I purchased a used take-off ALH intake manifold and installed that and now I have enough power to actually be of use and to drive.
Now, It's been a while since I've driven a 90 hp TDI (her golf is tuned to 130, and the Passat is 130 plus), and it seems like it's slower than those, but that's because those have a good 50% more power.
Anyway, I have it on the road as my primary car. Here are some images.

I wonder what's up with the original manifold

-J

Nice looking car; was the rear end involved in a collision leading to the new style trunk lid?

Odd troubleshooting though!

Newbie


just thought i"d say hello iam

Rick from north yorkshire

drive a

VW T4 1.9 TD But iam going to be converting her to a TDI soon

forum look packed with good info & peeps

PS she runs on 100% straight VO/WVO

2 tank sysyem & pulls great

Yes, I agree. There could be an "Introduction" section here where people can put their first post to say hello rather than choosing random posts to reply to.

It could also include some FAQs for the newbie with links to help them along.

eb2143 said:

Nice looking car; was the rear end involved in a collision leading to the new style trunk lid?
Odd troubleshooting though!

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Quite possibly the lid is a replacement.
The front passenger's door is a replacement. There is evidence of re-paint work at both front fenders. There were (likely still are) bits of broken safety glass in the interior under the seats and in carpet creases.
The undercarriage shows no signs of anything amiss so I don't think it was rear ended or otherwise structurally compromised.
I didn't bother with a carfax check because what I saw when I looked at it was enough for me.

Yeah, I scratched my head many times over the trouble shooting and cause identification.