ongoing coldstart problem
#1
ongoing coldstart problem
I will try to be as complete as possible about the problem. My boss has an 02 7.3 that had a bad cylinder and HPOP. About 1 1/2 years ago he bought a used engine from a junkyard. I did a compression test on the ground and found 2 cylinders with low compression that came up some with a wet test. I am a certified machinist and know that is the sign of ring problems but the junkyard insisted that it was valves and against my judgement the boss listened to the junkyard who told us to install it anyway. I have no way to scan it so we have had to rely on him taking it to shops with a scanner and he has spent more on diagnostics than it would have cost for an autoenginuity tester. Before I put the engine in I tested each glow plug on a battery and watched them heat up. After the install I hooked an ammeter between the battery and each glow plug through the harness to make sure there were no problems with the wires. I hooked the same ammeter between the glow plug relay and the harness to make sure that the relay was working and the rest of the harness was good. It has NEVER started right cold with the used engine. Even now with the night temps getting into the mid to upper 70s it still has to be plugged in. One shop insisted that is glow plugs so he bought the set of glow plugs, the undercover harness and valve cover gaskets. No change. The used engine is an e 99 model so I had to change the intake plenums, the turbo pedestal and turbo from the one out of the truck to the one I installed.When I installed the new glow plugs I did another compression test and 2 cylinders were about 370 and the rest were about 395. I have had a mechanical gauge in the HPO system and the cranking high pressure is as much as 1500 lbs. I don't remember now which set of injectors I put in it. I remember that the used engine had the ad injector in number 8 and the engine I took out didn't. The last time he took it to someone for diagnostics they told him it wouldn't complete the buzz test and the temp sensor is sending a temp signal of -50 degrees to the ecm. It sounds like it is only firing one injector until you crank it for 2 or 3 minutes. I know bad for the starter and batteries.. If it is plugged in it starts quickly but if it isn't it is like it is only firing on 1 cylinder. Where should I go from here?(besides maybe a red stick with a long fuse) Stock truck. No mods.
---AutoMerged DoublePost---
I meant AE in number 8 instead of AD.
---AutoMerged DoublePost---
I meant AE in number 8 instead of AD.
Last edited by gradyc; 08-03-2011 at 02:26 AM. Reason: Automerged Doublepost
#2
370 is fine for compression, the motor I am running right now is 320-325 and starts fine so long as you wait for the glow plugs first thing in the morning.
Have you checked or replaced the glow plug relay?
Need someway to scan it while cranking, HPO pressures and duty cycle would tell a lot.
Have you checked or replaced the glow plug relay?
Need someway to scan it while cranking, HPO pressures and duty cycle would tell a lot.
#3
I checked with the ammeter for current drain between the relay and the harness to make sure that the glow plugs were drawing the right amount of power, My high pressure mechanical gauge tells me the pressure is about 1500 but I don't know what the duty cycle is. One shop told him the IDM is bad but it would seem to me if that were true it wouldn't run at all. It starts fine if it is plugged in. Is it possible that the injectors are hanging and have to be warm to start operating?
#4
#5
#6
#8
#9
With the ammeter between the relay and the glow plug harness if there was no connection there would be no current flow. I am getting the correct current flow for all 8 glow plugs to be working. Watching the mechanical gauge in the HPO rail I am seeing 1500 psi during cranking mechanical reading. A drain back problem would seem to cause a delay in the high pressure reading coming up.
#10
Thread
Thread Starter
Forum
Replies
Last Post
burndiesel
24 Valve 2nd Gen Dodge Cummins 98.5-02
10
02-07-2023 01:15 AM
jeremy01995
12 Valve 2nd Gen Dodge Cummins 94-98
1
09-14-2015 06:34 PM
thurobred1320
12 Valve 2nd Gen Dodge Cummins 94-98
2
05-05-2015 09:26 PM