Engine/Transmission (1994 - 1998) Can a p-pump survive an engine fire?

[glhs]

I'm looking into possibly buying a 97 that has suffered an electrical fire under the hood on the drivers side. It melted the wiring harness on that side along with some sensors, radiator hose, master cylinder etc... I noticed the Cummins has plastic(?) covers on the side of the engine behind the pump which also look like they are melted/warped. I guess these give access to the lifters maybe?

The seller has all the parts to repair (minus the covers) but I wonder if damage could be done to the inside of the pump. If so, how much is a rebuilt pump?

Kurt

 

[McDowra]

you do have some springs in the pump which loose tension and need replacing. Average pump rebuild 600-800. 00 if that helps

 

[edmeyers]

those rubber covers are nothing more than sound dampeners from what i been told. if you run without them you will hear more valve train noise as for the pump there is a rubber diaphram in the AFC housing and a rubber gasket where the AFC bolts on to the pump i'm not sure what else is inside the pump i would be afraid of too much heat on these areas. i also think the pump is aluminium and heat will weakend or warp aluminium. just my 2 cents

 

[krs]

Sounds like another intake air heater failure... .



If it really got hot I'd agree about the springs and gaskets but think the warpage would likely be the worst of it and that would be bad. As I understand it the pump is like a little engine with pistons running in bores at very close tolerances. Warp the aluminum block and it'd be unlikely to work again.

 

[JGheen]

Originally posted by KRS

Sounds like another intake air heater failure... .

How would the intake air heating elements cause a fire? Is it a rare short that can be avoided somehow?

 

[bmoeller]

If the relays that control them stick on, they will overheat and catch things on fire. The heaters pull almost 100amps EACH.

 

[krs]

JGheen,



Do a search on the heaters a few different keyword ways and you should turn up threads about this. People, including me, have added various methods of switching off the heaters to prevent them doing this. A good one is to wire through the oil pressure switch so the heaters only run until the pressure is up.



Fires in that location have been described quite a few times in here, and probably a lot more that we don't know about. Thing is that except in the most severe cold most trucks start and run fine without the heaters so why risk it? IMO it's an emmissions control mostly.



On both of mine I just cut the tan colored wire to each relay and wired them to a switch in the cab so I can turn them on just to start. My '98 makes white smoke cold so I tend to run the heaters until it's warmed up, but my '97 runs smooth and clear without any heat at all. On a '99 or later doing this will set two codes, one for each relay, that don't light the dash light or effect the way the system works and reset easily with a scanner.



I think it's mostly due to aging relays that get sticky, so new ones would probably be another and correct fix.

 

[glhs]

Thanks for the replies.

I was told it happened from a battery install mistake. Something along the lines of the ground cables not being tight?

Kurt

 

[Texas Diesel]

Battery put in backwards? If that is the case then LOTS of stuff got burned up too.

 

[RT66DOC]

KRS -



Where are those relays located? Is the '96 similar as far as relay location and tan wires? Would please you describe in a little more detail how you wired the tan wires to the switch, i. e. , both to the same single switch? What kind of switch did you use?



Where I live it never gets below 40 degrees - ever - day or night - so I have little need for the grid heaters. I have even less need for a fire under the hood. I'd like to retain the option of using the heaters in case I ever travel to someplace really cold but want the option of switching them off.



Electronics are not my forte - or had you already picked up on that? TIA

 

[krs]

Hi Tom,

I think that this thread will have most of the ideas that have been applied: https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=66385&highlight=intake+heater



A search using "grid heaters" found it and more.



I think that all of the 2nd gen trucks are the same as far as this goes. The solenoids are driver side below the battery. One of the small wires to each is lighter in color if not actually tan.

 

[JGheen]

Originally posted by KRS

Hi Tom,

I think that this thread will have most of the ideas that have been applied: https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=66385&highlight=intake+heater



A search using "grid heaters" found it and more.



I think that all of the 2nd gen trucks are the same as far as this goes. The solenoids are driver side below the battery. One of the small wires to each is lighter in color if not actually tan.

KRS - Can I just pull out the relays to the heaters and not even worry about it since they will not be activated due to the missing relays and when those freezing days come again I can just put the relays back in and run the heaters then.



Also, since the 12v doesn't have a computer like the 24v does, is the IAT sensor on the 12v just used to cycle the heaters on and off until the intake air is up to where it should be, I think like 90F or something like that. If so, then could I just pull out that sensor and run a pipe plug there just for the summer months until it gets cold again in winter and put it back in along with the heater relays??



Joe

 

[RT66DOC]

KRS - thanks for info.

 

[krs]

Joe, I don't see why you couldn't do either of those things. Near as I can tell the heater not working has no effect on the engine's longevity or any other system's effectiveness in the 12 valve setup. In the 24 valve it might effect something considering how interrelated everything is, but I couldn't tell on mine. It will set codes - one for each solenoid, P0380 and P0382.



RT66, glad to help.

 

[JGheen]

Cool, KRS



That was exactly what I thought. Summer is a comin' round here so I think I am gonna save a fire from happening and just disconnect the heaters. I might even take them out and see how the engine performs with that heater restriction out of the intake manifold. It sure is nice to run a computer free, fully mechanical engine... ... easy troubleshooting analysis.



BTW, do you or anyone know what NPT thread that IAT sensor is?? I think it is 1/2" or 3/8" NPT but I thought i would ask so I can go out and buy the correct size pipe plug.