Author Topic: New diesel owner, help with diagnosis (Read 8609 times)

beerboyone · « **on:** March 29, 2006, 10:59:57 am »

I just picked up a '81 rabbit LS NA 1.6. It starts rough and shakes like a bastard until it warms up, then it just has a minor shake. The mechanical choke doesn't make any differance at all(yes it is actually moving the choke on the injector pump). It smokes a good bit until it's warm. does this sound like a timing issue or is it time for a new pump?
TIA,
Pat

bryanbryan89x · « **Reply #1 on:** March 29, 2006, 11:20:39 am »

Sounds like a block with a lot miles issue to me. How much oil does it burn? The symptons you describe resemble mine. I have 200,000 miles on my NA block. Mine burns a quart of oil per tank (sometimes more depending on how i drive it) , I get between 30-35 mpg. My pump timing is set to 1.00mm. I am going to re-ring the pistons this weekend, ill tell ya how it turns out...

beerboyone · « **Reply #2 on:** March 29, 2006, 11:36:43 am »

mine got 198,000 on it. i just got it and haven't even been through a gallon of diesel yet so i'm not sure how much oil it's going through. I need to get my other rabbit running before I can do a tear down on this to replace rings. thanks for the input.

wyldman · « **Reply #3 on:** March 29, 2006, 01:14:22 pm »

Can you isolate it to a single cylinder ? Crank the injector line loose one at a time while noting the RPM drop.When you find yoi dead cylinder,the RPM will not drop.

Compression test would be the next step,as well as leakdown testing to determine the cause if compression is low.

shwartzbewithyou · « **Reply #4 on:** March 29, 2006, 02:27:28 pm »

One quick test that I always do and you can do it on the fly is idling it and puting your hand in front of the tail pipe. Can you feel a dead spot in the air or is is a complete steady purr. That'll tell you whether your shake is a mis-fire or not. If not then the shaking could just be a broken motor mount. I think you need to first determine what it's shaking from, then you'll find your culprit.
Welcome to the world of newbie diesel ownership. I'm on my 3rd month now.

beerboyone · « **Reply #5 on:** March 29, 2006, 02:51:07 pm »

i'll go ahead and cancel the appointment I had for friday to have the injection timing checked. thanks. I'll try and determine if it's a dead cylinder.

beerboyone · « **Reply #6 on:** April 10, 2006, 10:47:49 am »

So i haven't been able to check compression yet but the problems have gotten worse. I was trying to track down an oil leak so I removed the upper timing cover and the airbox. sprayed a little brake clean around to clean up some leaking oil and put everything back together. I had a lot of problems starting her. I cranked and cranked and it just wouldn't start. There was some combustion as there was some smoke. but it would not run. So I had my roommate pull my car down the road and I started it that way. But it ran really rough and the idle didn't smooth out at all when it warmed up. It also smoked when reved after it warmed up which is something it didn't do before. this is my game plan to figure out the problem if there is anything I should be doing different please tell me as I am new to diesels.

1. crack injectors and observe idle changes.
2. check injector condition.
3. leakdown test.

thanks.

wyldman · « **Reply #7 on:** April 10, 2006, 10:53:18 am »

Sounds like your on the right track.Finding the bad cylinder is the first thing to do.

Then you have to narrow it down between an injection problem,or an internal engine problem.A compression or leakdown test will do that.

beerboyone · « **Reply #8 on:** April 10, 2006, 11:58:08 am »

where should I crack the injector line, at the injector or at the pump?

BlackTieTD · « **Reply #9 on:** April 10, 2006, 12:03:06 pm »

i'd do it at the injector.

wyldman · « **Reply #10 on:** April 10, 2006, 12:04:02 pm »

Crack them at the injector.

Loosen them all off first,then just lightly snug them back down.This way you won't have to fight with loosening them over a running enigne.Watch the little return nipples too,they are easy to bend or break with a wrench if your not careful.

Wear gloves and eye protection.Pressurized diesel is dnagerous.As long as you don't crack them too far,it won't come spraying out at you.

shwartzbewithyou · « **Reply #11 on:** April 10, 2006, 02:20:08 pm »

Is the PCV valve on the valve cover on these cars. I can't even recall. It seems coincidental that he pulled off the valve cover and the problems got worse.
Are you sure the PCV valve isn't clogged?

beerboyone · « **Reply #12 on:** April 10, 2006, 03:14:17 pm »

So I just got home from work and tried to start it up and it wouldn't run. So i opened the hood to look around and get a plan of attack and I looked at the fuel line and there is a lot of air in it. This wasn't the case last night. I guess I'll search around to figure out how to bleed the line and see if that helps. if not it's more than likely a bad injector pump right?

wyldman · « **Reply #13 on:** April 10, 2006, 03:50:26 pm »

If you have air in the line,it could be a plugged filter,a loose line,or the return fitting on the filter sucking air.

Check all the clamps,even the factory crimp ones,make sure everything is tight.Replace the filter,to eliminate it and the return fitting o-ring.

beerboyone · « **Reply #14 on:** April 10, 2006, 05:18:54 pm »

it looks like the return line might be leaking right off the pump. Can I replace this with rubber fuel line? does it need to be high pressure line?

Author Topic: New diesel owner, help with diagnosis (Read 8609 times)

shwartzbewithyou

shwartzbewithyou