1984 300TD Turbo Euro, What To Do Next...Chasing a Rough/Smokey Idle Problem - Page 3 - PeachParts Mercedes-Benz Forum

hcubed · #31 01-06-2010, 07:17 PM

Thanks for reminding me!

I haven't dorked with things much. Winter has come and it's cold and snowy in the Rockies! Performance seems to be getting worse, but I realized I haven't changed the fuel filters in a 1.5 years and about 15,000 miles. And I'm always suspect of the diesel we get up here.

Let me do that and test for the turbo play and get back to ya. I haven't replaced the return lines either so I should do that as well.

Going on vacation for a couple of weeks, but maybe by the end of the month I'll have a better update...

LJetronic · #32 01-06-2010, 10:28 PM

I would say just eyeball the timing by turing the engine in one direction only with a wrench and lining up the mark on the crank with the TDC mark, take the valve cover off and see if the cam mark is lined up also. If it's not CLOSE, you've got a timing chain stretch issue. This is not a complete method, but just a rough eyeball, the injection pump could still be out of time with relation to the crank and cam....

hcubed · #33 02-04-2010, 05:12 PM

Resurrecting this beastly thread. So I was on vacation for a while so haven't had a chance to do much. The idle/partial throttle shaking and smoking has gotten worse, especially when really cold. I finally took chaseinthesun's advice and checked the turbo shaft. Definitely play in all directions there. Looks like I'll need a rebuild.

I also met up with a German Mercedes mechanic from Hamburg who has worked on these things forever. He immediately said turbo, then timing, then the IP. It's probably over 200K now, so I'll rebuild the turbo and check the timing (it's time for a new chain anyway) and let you all know what happens.

Thanks again for the help.

dadette123 · #34 02-04-2010, 05:37 PM

As far as the back of the engine leaking oil, spray it off with brake cleaner so you can determine if its the valve cover gasket or the head gasket (back oil galley previously mentioned). If the engine has ever been severely overheated, head bolts can loosen and this back oil galley can leak out.

mdisav · #35 02-04-2010, 05:47 PM

How about replacing the fuel pump primer with a bosch sealed black pump style. Inexpensive and easy to do.

dadette123 · #36 02-04-2010, 05:54 PM

Quote:

Originally Posted by mdisav

How about replacing the fuel pump primer with a bosch sealed black pump style. Inexpensive and easy to do.

Good idea. One way to test if your primer pump is bad since it is the original kind, unscrew it and pump. If it leaks diesel up the shaft to the screw head, time to replace.

hcubed · #37 02-04-2010, 06:46 PM

The primer pump is definitely bad then. It spits fuel everywhere when I use it, but I thought it was supposed to do that...It's been on my list of things to replace (including the return lines on the injectors). Will order this week. Thanks.

I'll also take some brake cleaner and try to clean the gunk off the back of the engine to see where it's leaking oil.

hcubed · #38 02-18-2010, 12:52 AM

Ok, replaced the primer pump (I had trouble removing it and just ended up using vice grips on the pump body - very effective), replaced the fuel return lines, and rebuilt the turbo with a $100 kit from G-Pop Shop (http://www.gpopshop.com/). Still rough, smoky, stumbling at idle and under partial throttle. (Also cranked boost a tiny bit and installed a boost gauge.)

I'm going to drive about 200 miles tomorrow for work so we'll see if that cleans out residual oil from when the turbo may have been leaking before.

Next thing to check is timing (I just got a dial caliper to do the correct 2mm method) and, if it's not that, then it must be the injection pump. I haven't tried adjusting the rack damper, but I feel the problem is not related to that...

Will keep folks updated and thanks again for the help.

hcubed · #39 02-19-2010, 04:41 PM

200 miles didn't seem to clean much out. Still inconsistent stumbling and smokey idle. I'm in Boulder today through tomorrow morning.

Anyone in the Greater Denver area with a knack for debugging these things want to take a look and give their opinion? Thanks.

hcubed · #40 03-02-2010, 03:27 PM

Update.

So I checked the timing. It's around 12.5* via the 2mm valve lift method. This is 3.5* stretch passed new chain spec and 1.5* of stretch passed the 20,000km chain spec. So, not really alot of stretch, and it's not even ready for the smallest woodruff key (which gives an offset of 4* I believe).

Next I attempted to adjust the injection pump. There's very little room of adjustment and the pump was pretty much all the way advanced anyway. I pushed it the rest of the way (1/16" maybe at my alignment marks) and tightened back down. I wasn't really able to get the 1 drip per second, it was always a constant stream when pumping the hand pump (I have the updated sealed pump). Although the farther I pushed it advanced, the drips after I stopped pumping were slower and maybe closer to 1 per second...

Anyway, the car still ran like crap. Stumbling, smoky idle and partial throttle but fine in the upper RPMs. Maybe even a little faster do to the timing adjustment, hard to say.

However...I just finished driving about 200mi through high mountain passes at a fast clip and with the pedal all the way down (kickdown engaged) going up any steeps. When I got off the highway near Denver, it was running perfectly. Silky smooth idle and partial throttle and no smoke. I drove the car the rest of the way to Boulder (about 45min) and it ran perfectly!

What in the world is going on!? It hasn't run this well in months! I did fill up right before the drive out, but it's the same gas station I always use. I guess I gave it real long Italian tune-up. Could I have had a stuck ring or something?

I'm at work now and afraid to go start it again. I'm afraid it will be back to its old smoky habits. What pleasure when it's running correctly though!

UriahT · #41 03-02-2010, 04:30 PM

I hope for your sake it keeps running fine. A few repairs I've done only showed their benefits a day or two after.
That said, it sounds like it may be a rack dampener issue in some ways. There's no harm in fiddling with it, it's easy to get back in the same position.
A stuck ring is usually not eased out that quickly, but don't curse your voodoo either.

mdisav · #42 03-03-2010, 08:13 AM

I believe if the rack dampener is out of adjustment or in need of replacement it will shake but not give the smoking symptoms described.

I hope you have not been getting bad fuel all this time and now they have a new batch?

Also I notice it is a Euro, so I imagine there is no EGR. If there is an egr is it disconnected or bypassed?

Please keep us posted.

hcubed · #43 03-03-2010, 11:23 AM

Well, the shaking and lumpy idle/partial throttle was back after I went back to start it after work and again this morning. Strange. I'm going to mess with the rack damper today to see what happens - I've never touched it before.

It was federalized so it had EGR but I took all that off and blocked the ports on the intake and exhaust manifolds.

Could it be the lift pump slowly dying? Lack of fuel pressure? I don't have a way to measure fuel pressure here, but I think it's a cheap rebuild.

mdisav · #44 03-03-2010, 11:48 AM

Lift pump is an easy replace. I would get it used otherwise it will cost a bit. It is worth a try.

Carpenterman · #45 03-03-2010, 11:51 AM

One of the things I think you haven't done yet is to check the stretch on the IP's fuel bypass valve spring. Who knows, you've done just about everything else.