1987 300TDT cranks but doesn't start and other fuel system questions - Page 2 - PeachParts Mercedes-Benz Forum

#16 05-31-2005, 07:19 PM

Suddenly fuel primers (the newer ones...not the air leaking old ones) seem like nice things to have.

barry123400 · #17 05-31-2005, 07:22 PM

Here i am again. Kind of sorry if I sounded offensive about putting the contents of your old fuel filter into your new one and realised I had heard the folklore you mentioned before as well from some source or other. Just never made any common sense to me but I could be wrong in what I think. Just seen some pretty bad things come out of fuel filters like water and dirt before and for all I really know mercedes fuel filters may be different. But really cannot see how. As for the engine noise if it is a lifter mechanics used to add a little automatic transmission fluid to the base oil to devarnish them (sticky lifter) I suppose. I would wait and see if anyone else chimes in before considering it. Of course it will not deal with real wear in a lifter. Or perhaps check around. May save you a job or perhaps it is discouraged today. Mobil I may have the same action as I believe someone mentioned. Anyways glad you got the pump bled down.

swogee · #18 06-01-2005, 11:00 AM

barry123400,

Don't worry about it. I kind of wondered about dirt coming out of the old filter myself when I transferred the contents over. I may try filling the filter with Diesel Purge like sixto suggested next time so the the cranking time is decreased.

sixto,

I haven't noticed the metallic knocking sound recently, but I just replaced the belt tensioner lever, pulley, shock, and spring about a month ago.

The only noticable engine sound at this point is the ticking sound which seems to come from the valve cover. I figured the metallic knocking might have been a precursor to the ticking noise from the valves, but perhaps not.

Thank for all of the helpful ideas.

-Steve

P.E.Haiges · #19 06-01-2005, 11:24 AM

All this proves U shouldn't replace the fuel filters until necessary.

P E H

psfred · #20 06-01-2005, 08:04 PM

Next time you change the oil, change the two little O-rings on the center shaft. Yes, those "hard plastic" rings are actually rubber O-rings!

The noisy lifter is probably just flat from all that cranking with no oil pressure.

I only change fuel filters with a hot engine, it cranks faster. Fill the new filter with diesel purge or clean fuel on the outside holes and you will be fine. Better to slop some fuel around than to crank forever....

With a hot engine and the fuel filter full, it should actually start right up instantly, and purge the air out before the engine quits.

Peter

swogee · #21 06-02-2005, 10:59 AM

It looks like it may be time for new lifters.

At least I hope that is the main cause of noise. I started my 300TDT up again yesterday, and let it idle for a few minutes to see if the tapping noise would go away. No such luck. I then decided to drive the 300TDT to the gym, and after about going half a mile the noise from the engine bothered me enough that I turned around and I went home.

I listened to the noise intently at idle, and it seems to be coming from the valve cover area towards the front of engine around the number 2 cyclinder. Originally the noise was a faint ticking/tapping sound, but now it is a definite loud tapping noise. The noise almost seems to get slightly louder when I open the oil filler cap, but it hard to tell.

I am almost worried that it may be some other valve problem since the noise seems louder than what I remember to be a bad lifter noise, but maybe the lifter is totally flat.

Is there anything else I should look for when I pull the valve cover off?

Maybe all the cranking of the engine finished off the bad lifter?

Has anyone heard of FEBI brand camfollowers (lifters)? Are they decent as compared to the OE ones?

Thanks,

-Steve

sixto · #22 06-02-2005, 12:14 PM

Another source of noise is leaky delivery valve seals. My SDL lost a lot of what I thought was valve tapping when I replaced the delivery valve seals.

Sixto
95 S420
87 300SDL

speedy300Dturbo · #23 06-02-2005, 04:39 PM

I replaced the delivery valve seals on a 1987 300TD this weekend. The idle is noticeably smoother now. Keep in mind that after changing these seals, it takes a heck of a lot of cranking to get the engine started.

sixto · #24 06-02-2005, 08:47 PM

speedy, do you mean that it took a lot of cranking the first time after the IP went back together or every start since?

Sixto
95 S420
87 300SDL

speedy300Dturbo · #25 06-02-2005, 08:56 PM

Sixto,

The IP would lose prime after the car has been run and shut off. The result would be excessive cranking needed to get the engine started after sitting overnight for example. After the delivery valve O-rings and washers were replaced, it took a lot of cranking to get it going, but so far the IP holds prime and is completely dry around the delivery valves and hold-down plates.

tsiero · #26 06-02-2005, 10:26 PM

If you feel that you have a noise from an injector open the lines as the engine is running. Do this one at a time. When the noise goes away it is related to the injector line you just opened.

swogee · #27 06-03-2005, 11:24 AM

Thanks for all of the replies.

I think the noise is from the valves, since it has a somewhat metallic sound. It is also fairly loud. In addition, the engine starts right up when I crank it over now. The engine runs rough and smokes right after startup, but it smooths out fairly quickly. I also seem to recall the tapping noise was fainter before I changed out the fuel filter and then after cranking it many times, and flooring the accelerator (which revved the engine) I was finally able to get the engine to run.

If the delivery valve seals are leaking, would I be correct in assuming that the top of injection pump would have diesel fuel seepage from around the injector lines? I don't believe the top of the IP has diesel fuel on it, but I will double check. I'll probably change the delivery seals when I seal the oil leaks in IP.

Does anyone know if the "FEBI" brand of lifters (camfollowers) is as good as Mercedes OE?

Thanks,

-Steve

psfred · #28 06-04-2005, 01:35 AM

A bad tappet will make a harsh metallic snapping noise, just like a bad tappet or loose valve adjust on any other engine.

Check that the belt tensioner shock isn't bad first, it sounds almost exactly the same (metallic clank or snap) because the metal eye is banging on the metal bolt....

Unless you unscrewed the pressure valve holders for some reason, the seals aren't leaking, they don't fail in service. If one was leaking, it would cause both injector knock (sounds like someone driving a large nail into a solid oak slab) and seriously rough running below 1500 rpm. Shaking and some white smoke stone cold right after startup is typical of these engines. You can eliminate some of it by running the glow plugs 10-15 sec after the light goes on before cranking, or by replacing all the glow plugs ($18 or so each).

Peter

sixto · #29 06-04-2005, 02:25 AM

If cracking each injector line while idling doesn't isolate the tapping then it's not a problem with the fuel system.

Sixto
95 S420
87 300SDL

swogee · #30 06-05-2005, 12:25 AM

The belt tensioner shock I just replaced a month ago, so that pretty much leaves the lifters.

It looks like I will be replacing the lifters next weekend. I'll let everyone know if the problems is solved.

Thanks,

-Steve