How to quit smoking - PeachParts Mercedes-Benz Forum

dieselbenz1 · #1 05-10-2014, 11:36 PM

Ok I've been at this for a while 1992 124 602.962 I had a nailing and smoking problem at any rpm under load and no load. Checked everything in the fuel delivery system tried a different fuel source, pressure tested the fuel system. Replaced the head gasket nailing went away had a water and oil leak under the old gasket. Now it smokes under 1800 rpm no load and I mean smoke a lot not as bad a before the head gasket change. Ran moly purge no smoke at all. It idles ok could be a bit smoother as it once was. The nailing is completely gone. I change and balance the injectors before the head gasket no real change.

I'm now thinking maybe it's the fuel rail in the injector body. Could this be stuck to full fuel and how can I check that. Most of the codes are in error when I read the odb1 flashes.

Thanks

dieselbenz1 · #2 05-11-2014, 08:42 AM

I forgot to mention a few things 130k miles. Thick white smoke with a strong diesel smell now. The tank screen cleaned, all new crush washers and O rings now air in fuel system. Timing chain stretch less than 1 degree I'll need to get a IP locking pin to verify timing but the IP has never been touched.

GregMN · #3 05-11-2014, 11:05 AM

You do not need a locking pin to check the timing. (You only need to lock the timing on the IP if you are going to install it.)
Set your crank to the timing spec. for your engine (I think it will be 15 degrees after TDC)
Remove the timing port plug on the IP and, using a mirror and light, see if the timing ridge is centered in the port.

If the IP is over fueling, the rpm's would rise to burn it. (A diesel will not be over fueled at no load, until it reaches terminal rpms.)

Did you check the compression? Do a dry test, then a wet test.
If you find a low cylinder, then proceed to a leak down test to identify if the leak is valves or rings.

If you have a cylinder that is not burning it's fuel, that will cause smoke.

dieselbenz1 · #4 05-11-2014, 12:43 PM

I did a leak down prior to head gasket replacement which identified the water issues and oil entering cyl. 1. Good point to repeat this now. I did check to make sure the valves all sealed correctly and heald a seal with the head removed and all looked good. I may have to invest in a compression tester but was hoping to borrow one from a parts place but it seems they mostly cater to gas engines. Off to check the timing after Mother's Day lunch.

dieselbenz1 · #5 05-11-2014, 09:32 PM

I found the timing to be 17 degrees ATDC and I corrected it to 14.5 degrees. It starts and runs especially during the after glow cycle but right after it smokes strongly. I'm still thinking somehow some where air is entering the system just exhausted everything I know. Maybe I should go down the path and replace all the supply lines even though I had pressure tested everything?

GregMN · #6 05-11-2014, 10:48 PM

With the engine idling, open the fuel line nut at each injector, one at a time.
See if you find a dead cylinder.
If you find a dead cylinder, swap the injector with another cylinder and see if the "dead" stays with the cylinder, or follows the injector.

Maxbumpo · #7 05-12-2014, 09:03 AM

Really sounds like you have a bad injector to me.

You say that during the after-glow cycle, there is no smoke.

Idea: energize the glow plugs one at a time to see if the smoke clears. When the smoke clears, then you know which injector to replace. If you have a stout piece of wire, and you pull the appropriate connector from the glow plug relay, that connector has a pin for each glow plug, conveniently numbered to match the appropriate cylinder. Put your stout piece of wire into a pin position, touch to the 80 amp fuse (or the hot connection under the glow plug relay cover). Hold for 30 seconds or so to see if the smoke clears. Move to next pin and try again.

dieselbenz1 · #8 05-12-2014, 08:45 PM

I believe I have identified the cause of smoking and thank you for your inputs I was going to try them all. First of I dedied to run an other source of fuel once again. Hooked up 1/2 gallon fresh diesel 3 feet above the primary fuel filter, placed a large jar onto the return line. Once I opened the new fuel I noticed free flow of fuel through primary, lift pump and secondary. I thinking there should be some resistance that still puzzles me. Well started car and it ran beautifully until what I assumed was the afterglow maybe 45 seconds its is still around 40 degrees outside so that's about right. At that moment I saw lots of large air bubbles from the return line. So air out means air in. I went to the dealership and ordered a new filter the brand new mal? Which was installed is now suspect. Came back and thought to pull the bango bolt and found the upper o ring damaged. Put in a new o ring and thought to pull it to see what's up. The second then third o ring I tried all came out damaged. Must be some sort of defect in the filter or I have no clue how to install a bolt. My new theory is when the car sits the air some how escapes, when it starts someplace the air is entering the system around about the same time the afterglow also quits. This is also coincident with the air in the return line and the bumbling engine along with thick white smoke. This sure had me stumped and i'll be revisiting the down stream of the lift pump.

I'll update one I determine where the failure is provided I can figure out how to install a banjo bolt.

GregMN · #9 05-12-2014, 09:14 PM

Quote:

Originally Posted by dieselbenz1

I'll update once I determine where the failure is, provided I can figure out how to install a banjo bolt.

Just make sure you have a crush washer on each side of the banjo.

dieselbenz1 · #10 05-12-2014, 11:48 PM

The banjos I hope not to touch its the top nut on the filter with the o rings. I had difficulties obtaining the banjo when I had the filter assembly removed for the head job. I'm hoping one of those is not problematic but will know more tomorrow.

Thank you so kindly for your help and I won't forget your trick about the glow plugs.

dieselbenz1 · #11 05-13-2014, 07:23 PM

It still smokes I replaced the fuel filter pressure tested from the pre filter with 30 psi and clamped off the return. It held for 20 minutes. Put the return line in a jar still bubbles I am at a loss where the air is coming from. Is it possible its from Its from the IP?

GregMN · #12 05-13-2014, 11:46 PM

Do you have air bubbles going into the IP ?

dieselbenz1 · #13 05-14-2014, 12:13 AM

I can not see any through the brown clear line with a flash light behind it. Odd that when the car sits for a couple hours it start perfect runs for maybe 45 seconds great then smokes and baubles observed in the return. I'm thinking some how maybe in the filter the air escapes runs ok then air is sucked in but puzzling as that's a low pressure system. My newest thought just now will be to chase the suction side back to the tank. But I have not seen any leaks anywhere this has me stumped for sure.

Maxbumpo · #14 05-14-2014, 11:08 AM

You may have a rusted fuel supply line, which is allowing air to be sucked into the fuel system.

GregMN · #15 05-14-2014, 11:35 AM

Test for a single dead cylinder. Air in the fuel would be across all cylinders.
If you don't find a single dead cylinder, then proceed with the air leak search.