94 l400 bucking when cold

[ruggles]

Hi there I just bought a 94 l400 super exceed and it runs great when warm but it bucks pretty hard when cold. Any ideas what is causing this? I have never owned a diesel in my life so I am a super newb!

Thanks

[Mr. Flibble]

How did you buy it, and from whom did you buy it from?

I am assuming it is a diesel?

Does it produce smoke? If so, what colour?

Do you wait to start it until the glowplug light goes out?

[ruggles]

I bought it privately and yes its a diesel. I wait for the light to go out. how long should it take for the coil light to go out first thing in the morning? It seems like its a second or two. Once warm it runs great. I havent noticed any smoke but tomorrow morning I'll start it and go inspect the exhaust.

[CREGAN]

If you are not sure, just turn the key slightly to engage the glow plugs and then count about 7 seconds. It takes about that long for the relay to click and then you can start it. I don't even look at the glow plug light, I just listen for the click of the relay.

Craig

[ruggles]

If you are not sure, just turn the key slightly to engage the glow plugs and then count about 7 seconds. It takes about that long for the relay to click and then you can start it. I don't even look at the glow plug light, I just listen for the click of the relay.

Craig

Ok I'll try that tonight when I go home from work. Is the click pretty audible?

Thanks for all the quick info y'all

[CREGAN]

If you are not sure, just turn the key slightly to engage the glow plugs and then count about 7 seconds. It takes about that long for the relay to click and then you can start it. I don't even look at the glow plug light, I just listen for the click of the relay.

Craig

Ok I'll try that tonight when I go home from work. Is the click pretty audible?

Thanks for all the quick info y'all

Oh yeah, if it is working properly you will hear the click. Shut off all the accessories and you should hear it no problem.

Craig

[ruggles]

Yep I heard the clicks and it fired up no problem but it still bucks for quite a while like every 3-5 seconds.. I saw what I thought was some blue smoke in the side mirror so I got out and watched for smoke. Almost immediately after a buck, what looks like white smoke comes out. After it warms up it runs much better and no smoke. Any ideas what it could be? The PO said he replaced the glow plugs and injectors? or injector pump but I didnt get reciepts. He also said it ran smooth when cold which was bullsh*t obviously but it was a trade deal for whatever. Its a risk you take and I like to wrench so be it. Any ideas would be greatly appreciated!

[Dino]

I've had the same ordeal with my 4M40 Pajero. I sent out my injector pump to be rebuild in the late fall and didn't get to drive it until it got nice and cold. I had bought it in the summer and it started perfectly then so I have no idea how it started in the cold before doing the pump. I should clarify that I replaced the pump due to an external leak, the front seal had been done by the previous owner and that had not been an issue.

Anyway, same symptoms, when starting after sitting for 4hrs+ the temperature ranges from +1* to -4* it catches right away with a few seconds of glow plugs but it stumbles a little bit for 5 seconds or so. Below -4* it again catches right away but then missfires even more with plenty of whitish/greyish/bluish smoke and will do so for at least 30 seconds unless I rev up to about 1800rpm (which it struggles to do so). If I rev it up and let it sit there for a bit and then let it idle it's fine.

Things I've tried

- Changed plugs over to a manual switch so I can control how long they glow (I found that my glow temp sensor was faulty) - No change
- Replaced plugs with new HKT plugs - No change
- Installed a clear fuel line on the return side of the injector pump so I can check for air leaks easily - Noticed small air bubbles in the fuel
- Replaced all the low pressure rubber fuel lines with bulk fuel hose - No more bubbles, Slightly less stumbling, No significant change
- Re-checked fuel pump timing - Notched tooth was perfectly in line with the "N" mark when gear is meshed, and perfectly inline with "T" mark when pump is slid out (No change)
- Tweaked the injector pump timing by marking the housing, loosening it off and twisting it either way - No change to starting, but noticed slightly poorer performance under normal driving conditions, reverted to my starting point.
- Pumped the primer pump on the fuel filter housing before starting - No significant change
- Decreased the cold start advancement - Stumbled even more than before, and for a longer period of time
- Increased the cold start advancement - Reverted to previous symptoms
- Cold started the engine and increased cold start advancement until stumbling lessened (Pretty well maxed it out) - Still stumbles a bit, not as much, but it's still not right.

As you can see I've been dealing with it for a while. Besides the initial cold start issue, it's been running like a champ. I've learned to live with it, but I'm keeping an ear open for another idea to try. It seems to me that it's down to either one cylinder not glowing enough, or something in the cold start advance system that's not adjusted properly or malfunctioning. Right now the weather is starting to consistently hover around 0* so it might get one little puff of smoke or so, not something that I could continue to try adjustments with, so I might have to wait 'till next winter to figure it out :/

[Mr. Flibble]

Two other things to think of:

Change fuel filter (now that I think on it, mine is overdue)

Add an oil based "stop leak" to your fuel tank - this can prevent the seals in the fuel pump from degrading. According to the people on the Oz forum a yearly application can prevent many problems with the pump.

[ruggles]

I read about the stop leak. I also noticed this morning quite a bit of white smoke is coming out when cold once the bucking slows down. I also noticed an exhaust leak at the middle flange (puff of smoke when the miss happened). Do diesels get effected by exhaust leaks like gas motors? Any specific brand of stop leak I should use? I'll get some today. Ill get a new fuel filter as well.

Thanks!

[Dino]

The stop leak thing is usually a last resort to postpone the inevitable when your pump is leaking. The more vital thing is to make sure you use a fuel additive that has lubricity modifiers as the "Ultra Low Sulfur Diesel" fuel that we have here will cause the seals to dry out and crack if not treated. The stop leak will swell the seals in an attempt to get it to hold back the leak.

I might try a replacement filter too, although it had a fairly new Boshi filter when I bought it. I did try stop leak when my pump was leaking so maybe it did something to the filter that didn't get noticed until after I had the pump done.

[Mr. Flibble]

The stop leak thing is usually a last resort to postpone the inevitable when your pump is leaking. The more vital thing is to make sure you use a fuel additive that has lubricity modifiers as the "Ultra Low Sulfur Diesel" fuel that we have here will cause the seals to dry out and crack if not treated. The stop leak will swell the seals in an attempt to get it to hold back the leak.

I might try a replacement filter too, although it had a fairly new Boshi filter when I bought it. I did try stop leak when my pump was leaking so maybe it did something to the filter that didn't get noticed until after I had the pump done.

The guys in OZ were recommending a yearly treatment just as a preventative measure based on their long term experience with it. They saw that with a bad pump seal it would last a year before needing another treatment. Those that started yearly treatments did not need to replace the seals at all.

Not much data there on that, and the ULSD we get does cause pump problems. Apparently it is also causing pump problems with the VW Tdi engine pumps as well.

[ruggles]

The stop leak thing is usually a last resort to postpone the inevitable when your pump is leaking. The more vital thing is to make sure you use a fuel additive that has lubricity modifiers as the "Ultra Low Sulfur Diesel" fuel that we have here will cause the seals to dry out and crack if not treated. The stop leak will swell the seals in an attempt to get it to hold back the leak.

I might try a replacement filter too, although it had a fairly new Boshi filter when I bought it. I did try stop leak when my pump was leaking so maybe it did something to the filter that didn't get noticed until after I had the pump done.

The guys in OZ were recommending a yearly treatment just as a preventative measure based on their long term experience with it. They saw that with a bad pump seal it would last a year before needing another treatment. Those that started yearly treatments did not need to replace the seals at all.

Not much data there on that, and the ULSD we get does cause pump problems. Apparently it is also causing pump problems with the VW Tdi engine pumps as well.

Im going to get some lucas stop leak and put it in there tonight to see what happens. The po said new ngk glow plugs, new fuel injectors and fuel filter. No reciepts to back it up tho.

[Mr. Flibble]

Im going to get some lucas stop leak and put it in there tonight to see what happens. The po said new ngk glow plugs, new fuel injectors and fuel filter. No reciepts to back it up tho.

Just make certain it is oil based! ;)

Putting the radiator kind in your fuel would probably be bad.

[ruggles]

nope I won't be putting any bars leak in there lol