M1009 Odd smell on cold start...Can't find source....Baffled

[Asmoday]

M1009 Odd smell on cold start...Can't find source....Solved

Hello All,

So I'm gonna need some help finding this issue. I have noticed that over the last couple of weeks I get a odd smell in the engine bay right after a cold start. It generally dissipates after a minute or two but it's there long enough to notice the odor inside the cab. It kinda smells like burnt electronics or power steering fluid. The engine fan blows the smell around so I can't seem to source exactly where it is coming from or what it is and I have searched everywhere. It does not do it when warm.

I originally thought maybe it was the starter relay or GP controller card inside the truck but it's not. I had already done the "Doghead" starter relay mod when I first got the truck and its been flawless. The relay does not get warm etc. The GP controller card looked OK and the system tested out correctly with a Fluke but since I had a new Legacy card from CUCV electrics I threw that in there as well eliminating the possibility of that being the source.

The resistor bypass mod was done last year and AC60G's were installed with proper clips etc. The GP relay is a heavy duty Trombetta unit and I swapped a new one in just in case. The voltages at the GP relay when the system cycles all all correct. The system cycles correctly. The truck has always started immediately when cranking and that remains the same. Both batteries are new and the drivers side alternator is brand new since the old one had a bad diode causing the GEN 1 light to faintly glow with the heater on. The pass side alternator has not been changed but it puts out a correct charge. All battery cable connections are clean. Lights are bright etc. etc.

There are absolutely no fluids leaking anywhere on the truck plus the truck would not be hot enough anyway to cook any fluids as again the issue is only when cold. All fluid levels have remained full. I even went so far as to use a UV light to search for leaks in the dark and nothing. Everything looks great in the engine bay and I have not seen any wiring so far that exhibits signs of overheating etc.

So anyone have any suggestions? It has the direct drive starter and it appears OK. It does not emit any heat after starting, literally cold to the touch and the connections look good.

The only possible clue I can think of is about the time when this started I replaced the fuel filter and when I was doing the short cranking cycles to bleed out the air I did notice a similar smell. I would only crank it a few seconds and then let the starter cool. I only had to do this a few times and she fired right up once fuel was coming out of the bleed tube. But...I did notice the same odor.

Could it be the starter or maybe the pass side alternator being stressed after the glow plugs cycling and the cold start?

Thanks...!

 

[dependable]

Just a guess it might be starter related, but your truck starts so well that it has not been a problem yet. You could look around the brushes for wear or frayed wire, clean the commutator, see if there is any play in end bushings. I always suggest stocking a spare starter (and bolts), even if it a cheep import. Sometimes a starter will sound a little 'harsher' if it is on the worn side too. You could disconnect the IP and crank it for 10 seconds and see if starter smells or has wisps of smoke.

 

[Asmoday]

Thank you for the suggestions. I do have a replacement direct drive starter standing by....I just don't have the time right now to swap it out. I'm kind of afraid to go out there and crank it a bunch to see if it smokes...LOL.

Do you think the problem could be in the solenoid at all? I would think I would smell it after every start. Why do I only smell it when cold if it's starter related?

 

[dependable]

If starter is in good shape, it should be able to crank for 10 seconds with no problems or smoke (not that you would want to do have to that every day) ok to try it for 5 seconds. Could be solenoid, but more likely starter wear like bushings (which causes rotating part to rub against outside coils) or a problem around the commutator or brushes. Due to the mass of the original non gear reduction starters, the bushings on each end do develop play, which causes friction. This seems to be one of the common reasons for failure on this starter.

I am just guessing, that when truck is warm, it may take such a short time to start it that the problem does not show itself.

 

[Triple C]

If it is an acrid smell that kind of burns your nostrils, maybe it is exhaust escaping from a cold exhaust manifold. I have a 6.5 that does that and it will just about make your eyes water. It stops very quickly. Just a thought.

 

[Barrman]

Are you familiar with the sweet smelling blue/white smoke that happens when the glow plugs don't work as good or as long as they should and the engine has to crank 3-10 seconds to start?

Is it that or the burned wiring smell you are getting?

Just trying to help narrow down wiring or exhaust.

 

[Asmoday]

Ok...I have found the problem. In the end it was something very simple as I kept thinking..."what's happening electrically only when starting the truck cold"? Obviously the glow plugs cycling...right? Well...I had checked the relay and all the voltages more than once and all seemed good. I decided to get up in the engine bay while someone turned the key on a cold start and sniff around. Voila...the smell...! I followed my nose and it led me to the portion of fusible link wire at the end of the 12V accessory lead from the rear battery that feeds the 12V buss block on the firewall. This block is what most of us tap onto when converting to the 12V GP relay system.

For some reason when the relay was cycling the glow plugs it was causing an excessive load on the 12V lead from the battery and being the fusible link is a smaller gauge of wire it started getting "real" hot and I do mean HOT cooking the insulation. Someone in the military had actually replaced the stock blue 12ga fusible link portion with a orange 10ga fusible link portion. Probably if it had still been a blue portion it would have blown.

I replaced the relay and it stopped the excessive load on the 12v junction block. Everything measured correctly on the GP relay that I removed...coil resistance etc. but something internally is amiss. It was tossed.

Now...this relay was only about six months old and a nice USA made Trombetta unit so I was a little surprised that it developed a problem. I have replaced it with a very heavy duty unit that has a 200amp continuous load rating with silver contacts. I was able to pick up a few at a great price from an online auction site I won't name or link to... Do a search with the info provided below.

Here's a pic. These are NOS US Made units and I was surprised how heavy they are. Be advised the new stock ones you get from a dealer are made in Mexico. Grab some before they're gone...!



Prestolite
SAS-4202, 15-133

I will be running a dedicated line for the GP relay directly to the battery in the near future. I will also put the 12v feed line back to stock by replacing the wrong size fusible link wire with the correct blue 12ga section...