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6.5L Diesel Engine Discuss the 6.5 GM diesel engine & associated components. Automatic transmission questions & problems belong in the 4L80/85 - 4L60E - 6L90 Transmission Forum

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Old 05-25-2016, 11:07 PM   #1 (permalink)
Wineinger
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Issues after motor swap

Hi, I am new to the forum but I have read numerous posts as a guest and they have been really helpful.
I bought a 94 2wd 2500 last summer. A few months ago, I damaged the transmission while stuck in the snow. I then bought a 4x4 with a bad motor. During the past few months this I have swapped the motor out of the 2wd into the 4x4. The project took a lot longer than it should have but I have learned a lot.
I just got the truck back on the road this past weekend and I am experiencing a few issues that I do t quite understand because the motor ran fine before the swap. I used the ecm and the pmd from the 2wd because the 4x4 ecm would not start the truck and I had just replaced the pmd a month or so before the swap. Everything else is from the 4x4. The wiring harness is spliced in a few places.
The issues I am having are:
1) The check engine light comes periodically while driving down the road usually after picking up speed but only for a few seconds then it turns off again. I can hear the turbo whistle much better on the 4x4 than I did when the motor was in the 2wd but I just assumed it was because of the straight pipes. Could the engine light and the louder turbo be connected or is the light caused by some electrical malfunction?
2) The rpms are running higher than they should be according to a calculator I found and completed. Before the swap they were where they should have been and I have the same alternator and pulley and computers as before so I do not understand this at all. Any help y'all can give me would be greatly appreciated. I know 6.5s are sensitive motors and I do not want to ruin anything. Thank you in advance.

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Old 05-25-2016, 11:16 PM   #2 (permalink)
OkDually
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Quote:
Originally Posted by Wineinger View Post
Hi, I am new to the forum but I have read numerous posts as a guest and they have been really helpful.
I bought a 94 2wd 2500 last summer. A few months ago, I damaged the transmission while stuck in the snow. I then bought a 4x4 with a bad motor. During the past few months this I have swapped the motor out of the 2wd into the 4x4. The project took a lot longer than it should have but I have learned a lot.
I just got the truck back on the road this past weekend and I am experiencing a few issues that I do t quite understand because the motor ran fine before the swap. I used the ecm and the pmd from the 2wd because the 4x4 ecm would not start the truck and I had just replaced the pmd a month or so before the swap. Everything else is from the 4x4. The wiring harness is spliced in a few places.
The issues I am having are:
1) The check engine light comes periodically while driving down the road usually after picking up speed but only for a few seconds then it turns off again. I can hear the turbo whistle much better on the 4x4 than I did when the motor was in the 2wd but I just assumed it was because of the straight pipes. Could the engine light and the louder turbo be connected or is the light caused by some electrical malfunction?
2) The rpms are running higher than they should be according to a calculator I found and completed. Before the swap they were where they should have been and I have the same alternator and pulley and computers as before so I do not understand this at all. Any help y'all can give me would be greatly appreciated. I know 6.5s are sensitive motors and I do not want to ruin anything. Thank you in advance.

Welcome to the Forum.

What year,make,model is the 4wd you swapped the motor into?

Did you check for any codes?
Any exhaust leaks?
Any Vacuum leaks?
What brand of PMD did you install and what # resistor is in the PMD?
Notice any other symptoms like black smoke or fish biting or surging?

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1996 K3500 6.5L,( "F" Eng #141 cast block) 5 speed manual, crewcab, dually longbed: 208,000mi.
Diamond Eye 4" Turbo Back Exhaust w/2.5" Flo-Pro Crossover
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TD-Max boost controller - Kennedy Diesel
OPS extension hose - Leroy Diesel
Glow Plug Harness- PT Wiring Solutions
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PMD w/#9 resistor and Re-Location Kit, mounted to bumper - Leroy Diesel
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Old 05-25-2016, 11:22 PM   #3 (permalink)
Glagulator
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Welcome. Are the trucks autos or standards?
The tach is driven by the alternator, the PCM has nothing to do with it.
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99 CREW LONG SRW C3500 work truck 199k+ mi. orig. motor & trans 4.10, modded engine harness, new oil cooler & lines, all new front end parts and poly bushings, trans poly mount, all new brakes.
96 SUBURBAN K2500 wife's truck 210k+ mi. orig. motor & trans, 3.73...
95 C2500 Suburban 6.5td HO w/p, timing set, HB & pulley, all rubber hoses, modded engine & main harness, converted to OBD2, PMD to bumper...
95 C1500 Suburban 6.5td rebuild tranny, convert to DB2, replacing as many parts as I can.
96 C2500 Suburban 7.4L converting to 6.5td w/ DB2, 4L80, 3.73
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Old 05-25-2016, 11:30 PM   #4 (permalink)
HeavyChevy95
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Scan tool and TDCO and Backup Fuel procedures neccessary, most likely..

Also, check for and report any DTC(s) found.. OBd1 models only need a paperclip to check for and clear DTCs..
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Old 05-25-2016, 11:33 PM   #5 (permalink)
Wineinger
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The 4x4 is a 94 same year as the 2wd. I bought the pmd, the #9 resistor, the relocation kit, and pmd cooler all from Heath diesel when mine went bad. I have not yet had a chance to get any codes. I am not sure how to do this some of the stuff I read says that depending one the code, it may clear itself after the light turns off and that auto parts store computers may not read them. I have not been able to find any vacuum leaks yet but they maybe some that I have not found yet. The exhaust is welded from the turbo back so there are no leak there but one of the studs is broke on the driver side manifold. However I do not think it is leaking from there.
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Old 05-25-2016, 11:39 PM   #6 (permalink)
Wineinger
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There is a little more black smoke on hard acceleration than there was before the swap as well. Both transmissions are automatic. I do know that the tach reads off the alternator but it is the same alternator and pulley as before along with the same ecm. That is the confusing part about that.
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Old 05-26-2016, 12:10 AM   #7 (permalink)
HeavyChevy95
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Unless your info is from the 'horses mouth' persay, forget it.. Haynes, Chilton and most all unauthorized pubs are only good for wiping your cash with however GM techs are often the sources of most 6.5 misinfo. Go figure..

See "Service Engine Soon" (SES) starting on page 98 of 'GM 6.5L Turbo Diesel DS4 Student Handbook' (download and save link in my signature).
Midpage 99, see 'Reading Diagnostic Trouble Codes At The MIL'

Last edited by HeavyChevy95; 05-26-2016 at 12:14 AM.
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Old 05-26-2016, 12:56 AM   #8 (permalink)
OkDually
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Quote:
Originally Posted by Wineinger View Post
I have not yet had a chance to get any codes. I am not sure how to do this some of the stuff I read says that depending one the code, it may clear itself after the light turns off and that auto parts store computers may not read them.
You can pull any codes for an OBD1 System just by using a paperclip and reading the info in the link below for a "how to".

https://www.dieselplace.com/forum/63-...des-obd-i.html
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1996 K3500 6.5L,( "F" Eng #141 cast block) 5 speed manual, crewcab, dually longbed: 208,000mi.
Diamond Eye 4" Turbo Back Exhaust w/2.5" Flo-Pro Crossover
AirDog II DF165 w/ tank sock delete - XDP
TD-Max boost controller - Kennedy Diesel
OPS extension hose - Leroy Diesel
Glow Plug Harness- PT Wiring Solutions
Glowshift Maxtow EGT,Boost, Fuel gauges
Boost & Fuel Pressure Bolts - Leroy Diesel
2/0 Battery Cable Upgrade - PT Wiring Solutions
PMD w/#9 resistor and Re-Location Kit, mounted to bumper - Leroy Diesel
GM-5 Turbocharger
4.10 gear ratio
OptiLube Winter Formula


Proud member #1039 of The 3500 Dually Club

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Old 05-26-2016, 02:28 AM   #9 (permalink)
nsdtk
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Whats the gear ratio on the axles of the 2wd and 4wd that might explain the rpms
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1994 Chevy C3500 6.5L NV4500 ,Outrider by Unique Conversion.Dually club # 1077, DE exhaust, Pressure Referenced Wastegate, LED upgrade in progress, In cab Dorman PMD, optical sensor filter removed ( shocked when i saw it was in there). LP Relay mod. Ate a valve, 117,900 Miles. RIP Engine #1,now 2016 GEP Optimizer powered and QuadStar tuned.
1995 GMC C1500 non turbo 6.5L 4L60E xVDOT truck. High Idle mod. Grey PMD on a FSD sync #9 resistor. Vaccum pump removed. No more EGR. Air intake opened up. 3 inch exaust on a high flow muffler. New push rods, Rockers arms at 246k. Was over10,000ths wear on the rocker arms.1998 style High Flow oil pump installed. Spins tires with little throttle again. 6.2 Injectors.Back running 80mph @ 21mpg. All this and now it won't roll black smoke at all. Just acts like a rocket ship 2004 Leather bucket seats from a Tahoe installed. That was a engineering fiasco glad that's over. Dorman PMD now, Grey one died. Tried number 5 resister again went back to a 9 just a dog with out it.OPS sensor rewired to remove load , fuel pump totally rewired as well. Now QuadStar tuned.
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Old 05-26-2016, 04:46 AM   #10 (permalink)
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Yup. Since the 2wd truck had lower RPM than the 4wd truck, either the tires are smaller or the ratio is shorter (numerically higher) than before. Most likely, the 2wd truck had 3.73:1 and the 4wd has 4.10:1.

Also, since the 2wd truck computer is in play, and you are getting codes, the transmission may not be locking the torque converter or shifting into 4th gear...

Ya gotta find the codes. I use gmtd tech and it works great. A paper clip will generate the flashing light to count...

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Last edited by vstech; 05-26-2016 at 04:49 AM.
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