New Friend Questions. '92,300D,2.5TD - PeachParts Mercedes-Benz Forum

Phillytwotank · #1 02-13-2015, 11:37 AM

In effort to smash through my learning curve on the w124 chassis and the OM 602 engine I have a few questions i wanna throw out there for y'all. Please chime in with any Answers, Advice

New to me 1992 300D 2.5 turbo diesel has been pretty good for the first couple of weeks on the road making my 96 mile daily commute. 27 MPG first full tank of fuel (B99). All the most important things are working as they should. Cruise Control, Climate Control, Brakes, Lights, Transmission shifts good, Horn.. all that goodie stuff.

Just a couple of things that are bugging me.

Radio: I will be replacing the original radio as soon as i can rangle up some funding. until then, the original radio works sometimes. When it does it everything sounds fine. When it doesn't i will power on but the display will remain blank and it will flash " E 2" then go off again. Is there an easy fix for this to get me by for a bit until i can get a new head unit in there??

Turbo: I've not yet had a chance to Tee in a proper boost gauge but my seat of pants boost gauge tells my that something is up with the turbo. The damnedest thing... the turbo seems fine until the engine gets up to temp. When it hit about 80c the turbo seems to go away.

I've read up un the pressure waste gate swap and i have the part in the garage ready to do the swap. I did temporarily straight pipe vacuum to the waste gate and it would peel your eyes back with acceleration. So, i feel pretty confident that the problem is somewhere there on the control side of things.

My question is...has anyone ever experienced anything like that? will the pressure waste gate swap solve that problem as well?

Lifter Noise?: Very first thing i did was change the oil to rotella synthetic. That along with the new injectors from Greazzer and she's 85% quieter than before. Still experiencing some Clacka Clacka. Now i know that some of that is to be expected with these but compared to what i'm used to with the '78, that sounds like somebody's hemming up a pair of pants up there, i don't think that i can settle for less than the quietest it can be.

Is there a definitive way to check the lifters?

I'm planning on opening up the valve cover tomorrow to check the chain and to check the lifters at the same time.

I dont want to make a too long post so i'll stop here for now.

Thanks all

sixto · #2 02-14-2015, 10:12 PM

Radio - no help on diagnosing the problem but replacing the radio is more work than on other cars because the rear speaker wires and antenna cable connect to a module in the trunk, not to the unit in the dash.

Turbo - there is an excellent change a pressure wastegate will solve the turbo problems.

Lifters - the 2.5 head gasket can get flaky to where it disintegrates and debris clogs the oil supply to the lifters. No fix there other than replace the head gasket and clean the oil passages in the head while you're at it. To test the lifters, set the cam lobe away from the lifter than press down on the lifter. It should be darn near impossible to collapse the lifter. Any lifter that feels softer or mushier than most is suspect. There is a sequence to loosening and tightening the cam towers so study the manual before pulling the cam. Do NOT use a magnet to remove lifters as suggested in the manual. Use a valve grinding suction cup as suggested in a service bulletin that never made it to the main manual. You don't want to magnetize the lifter and cause it to trap ferrous debris in the oil.

Check that the noise isn't coming from the serpentine belt tensioner damper. The pivoting end bushings tend to wear out more quickly than the damping element, particularly on aftermarket replacements. With the engine running, use a screwdriver to pry the upper attachment from the head. If that quiets the noise, you need a new damper. There's also a lower attachment that can make noise.

Sixto
MB-less

jay_bob · #3 02-15-2015, 01:23 PM

I found an old thread on the multimedia section.
You should have a 1432 three piece radio.
Head unit and 2 controllers in the trunk, one is the tuner and the other is the amp.
Head unit is dumb and just has the cassette drive and controls the tuner unit via a bus cable.

Radio error code!!!

These can be upgraded to aux input by Becker.

Phillytwotank · #4 02-16-2015, 01:22 PM

Thanks for the replies.

Radio: when it's all working it sounds great and i dont mind having just the tuner and the cassette for now. Looks like it will be fairly complicated to hook it up with an aftermarket set up. I've heard about the aux input mod. i may have to look into that.

Turbo: got the turbo out and was able to test the old vacuum wastegate with the trusty dusty midyvac. it would barely work with constant pumping and would not hold vacuum at all. So, i assume that was THE problem. new pressure waste gate has been swapped, adjusted and tested now i just need to tap in somewhere for the pressure supply and put everything back together.

Lifter Noise: I opened up the valve cover to check everything and found that the lifters look fine to me and were all very difficult to depress with a wooden dowel. so, i'm moving on from the lifters for now.

Noise in general: I found the belt tensioner to be in pretty sad shape. Bearing looked worn and the main BOLT TO THE BLOCK WAS FINGER LOOSE! Just kinda flapping in the breeze up there. So, i'm glad i caught that now. I'll probably go ahead and replace the tensioner and be sure that it is installed correctly. So, i'm thinking that some of the clacka clack may have been coming from there.

Timing Chain Stretch: I don't own a dial indicator so using the "marks" method i see 3-4 degrees of chain stretch. FSM says 3-10 replace so i figure that it's still got some time before it becomes a have to do job. I will definitely be checking/adjusting the injection timing when i get it all back together.

THE BAD NEWS: To be continued....

Waz · #5 02-16-2015, 02:15 PM

While you are replacing the belt tensioner I can't tell from your post if you intend to replace the tensioner shock or not. I would suggest that you replace it also.

I have seen and heard at least 4 OM60X engines that sounded like the engine was about to rattle apart that turned out to be worn bushings on the tensioner shock.

Phillytwotank · #6 02-16-2015, 03:41 PM

i wasn't planning on doing anything to the tensioner before i removed it the other day and discovered how bad it looks. guess i'll be looking at doing the whole job on that when i get to it. Thanks for the suggestion.

Phillytwotank · #7 02-16-2015, 03:42 PM

Does that look like a head gasket leak to y'all??

engatwork · #8 02-16-2015, 04:13 PM

Classic symptom of head gasket failure.

Skid Row Joe · #9 02-16-2015, 04:22 PM

Yowser !

Phillytwotank · #10 02-16-2015, 05:01 PM

Yeeaahh. I first noticed that it was using a little coolant. then i saw all that when i go the turbo and exhaust off.

I knew about the head gasket issues on the 602 going into this and i was prepared to have to deal with it. One of my main criteria in my shopping was to find one that was nice enough all together for it to be worth taking care of something like this and rolling with it.

Given the condition of the pain,body,interior is very good i'm not sweating it too much.

Skid Row Joe · #11 02-16-2015, 05:26 PM

Quote:

Originally Posted by Phillytwotank

Yeeaahh. I first noticed that it was using a little coolant. then i saw all that when i go the turbo and exhaust off.

I knew about the head gasket issues on the 602 going into this and i was prepared to have to deal with it. One of my main criteria in my shopping was to find one that was nice enough all together for it to be worth taking care of something like this and rolling with it.

Given the condition of the pain,body,interior is very good i'm not sweating it too much.

That's the spirit!

vstech · #12 02-16-2015, 08:45 PM

If the tensioner bolt was flapping around, you may be looking at a new timing cover...
Make sure you check it out VERY WELL! Any wear or cracking there, and it's gotta be changed.
It's possible it just worked loose from the rattlin, but it's equally possible it was changed in The past, and the spacing washer was left out... Be sure the washer is there.
Oh, apparently the tensioners are cheaply rebuildable.

Phillytwotank · #13 02-17-2015, 04:39 PM

Quote:

Originally Posted by vstech

, but it's equally possible it was changed in The past, and the spacing washer was left out... Be sure the washer is there.
.

Yeah! it was missing the washer.