73-87chevytrucks.com
General Site Info => General Discussion => Topic started by: Irish_Alley on January 25, 2017, 10:10:16 PM
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Its a 2500 burb. Bluebook for 5k and i got him to 4k before i even showed up by getting him to take his tires/rims off. so hes replaced the PMD box back in Oct and had it running then let the tags run out last month. i show up and start looking at it asking him about the motor and he said he shudders at low speed only when cold. it had ran for a few minutes and we took it for a test drive. and sure enough it starts shuddering i noticed it when i would go easy on it and when cruising at low speeds about 25ish. drove it back to his place which is only a few hundred yards and park it. he swore it would stop as soon as it warms. but without tags on it i didnt want to drive it till it warmed up.
ive had a few experiences with the 6.5 and each one of them is telling me to RUN. but if someone knows the issue or what to check i might try and talk to him again
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If it truly does go away when warm, only 2 possibilities I can think of, air in the fuel, or injectors aren't in the best shape.
At 4grand I probably wouldn't risk it, going down to 2.5 or 3G it might be worth it if you do all the work yourself and have access to a GM tech scan tool to verify TDC and timing.
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Injection system is my guess. Pumps are known for that. Timing could be another reason. The 6.5 is known for issues not so much internal but the injection and pump timing will cause a dirty ride
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Curious of the year and is the PMD box relocated or not.
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pmd was relocated and 99. he tossed a lift pump on it and it supposedly fix it so he sold it for 5k. oh well i dont like the 6.5 anyway and i wouldnt have paid 5k for it
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That's probably injection pump or PMD problems. The DS4 is great as long as it's working properly. Hook a Tech 2 up to it and look at the PWM Solenoid closure time.
http://www.dieselplace.com/forum/63-gm-diesel-engines/21-6-5l-diesel-engine/655570-ds4-injection-pump-closure-time-follow-up.html (http://www.dieselplace.com/forum/63-gm-diesel-engines/21-6-5l-diesel-engine/655570-ds4-injection-pump-closure-time-follow-up.html)
PMD relocation is more trouble than it's worth. If the mounting surface is flat and smooth with no corrosion and the pump is in good shape with heatsink grease or new heatsink pad the FETs in the PMD shouldn't cause you trouble.
Don't don't don't run her below 3/8 of a tank of fuel. Fuel cools the injection pump and electric fuel lift pump. If there's not enough fuel to carry heat you can have issues.
Injectors are not difficult to rework. GM used the same style Bosch injectors on the 6.2 & 6.5 as the 1980's VW and Mercedes diesels so there's a wealth of info online about pop testing and rebuilding them yourself. You can build a pop tester with a porta power ram or bottle jack, a 3,000 PSI 4" or 5" liquid filled gauge, and the proper plumbing.
In any case it's not worth $4,000 with DS4 issues.
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yeah before i even knew about the ds4 i told him 4k then i get there and after the test drive i was like awww heck no. i wanted to run away but was trying to be nice. i was going to shoot him the price of 3k but hes now sold it with a new lift pump. idk maybe the lift pump was sucking air, im lost. the guys over at diesel place said it could be the pump. in a way im glad the truck isnt my issue. but i would of loved to have a burb with a diesel i dont even know if the 2000s came with them
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I'm sure you will build a Cummins powered Suburban in the future. Looking forward to the build.
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pmd was relocated and 99. he tossed a lift pump on it and it supposedly fix it so he sold it for 5k. oh well i dont like the 6.5 anyway and i wouldnt have paid 5k for it
I would lean towards pump problems since the PMD has been replaced and relocated. I don't care for the 6.5 or the 6.2. I have worked on them for almost 30 years and the first thing I did with my truck was to replace it. Sounds to me like you made the right call.
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yeah, his response was he sent me a text about 6ish saying that he sold it for 5k and replaced the lift pump and it didnt act up for the 2 hrs he was driving it. the day before the truck didnt have tags and he really didnt want to go up the road the abs light was on and there was no brakes. i mean i had to go to the metal to stop when she was up to speed.
and he said once she warms up she doesnt act up any more. so him driving it for 2hrs after he got off work had time to change the pump and drive it for 2 hrs keeping it warm so it wouldnt warm up then sold it to some kid (im guessing) that heard diesel and wants to roll coal. these kids are the reason why these diesel trucks sell for above blue book. i told him i was still sure it was the injection pump he said na cause it was just replaced 2 years ago. i dont care if it was replaced 2 months ago it can still go bad.
long story short as much as i wanted it im glad it didnt work out and i feel sorry for who bought it for 5k and now they might have to put another grand into a truck thats maybe worth 4 at the max
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Sounds like the guy is a true used car salesman.
Warm that baby up so the dead glow plugs don't affect starting and the cold sticking injection pump PWM solenoid doesn't rear its' ugly head.
I run away if the vehicle is warmed up before I get there.
No valid plates to test drive? Again I'll hit the road no questions and no apologies.
If they guy complains I'll tell them they wasted my time and I'm not happy.
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I concur. There is no way a mechanical lift pump problem would have allowed it to run better when it warms up.
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I concur. There is no way a mechanical lift pump problem would have allowed it to run better when it warms up.
Actually it's fairly common for the diesels to run rough then smooth out when warmed up on a bad lift pump, although power may be lacking, and you lose some top rpms. Reason is the injection pump can pull fuel from tank, although it will shorten the life span, and when cold the clearances in the pump are greater so it has a harder time pulling fuel.
That said I'm not going to deny there could be other issues, either with injectors or the IP, or even the PMD.
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I have never known that to be the case before. News to me.
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i was confused about how smooth it was when under hard acceleration. and you only noticed the issue when you kept the throttle steady to match the speed.
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I concur. There is no way a mechanical lift pump problem would have allowed it to run better when it warms up.
The 1994-2001 DS4 6.5L uses an electric lift pump mounted on the frame under the driver seat.
The lift pump might've been the only problem but I've seen similar operation with injection pump solenoid issues. Properly rebuilt DS4 pumps are not cheap and they're a pain in the neck to replace.
The DS4 isn't oogy boogie or a dark art or whatever other comment that can be made about it. They require a little more care than the old DB2 on the 93 & prior 6.5L & 6.2L engines. Again the snake oil salesmen that tell you you need to relocate the PMD are full of it. I've run five DS4 equipped trucks for over 300,000 miles without trouble from the PMD. I did remove the PMD, dress the mounting pad so it was flat and smooth and re-install them with heatsink grease.
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The more I read, the more I learn something I did not know before. Good information on this site.
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yea this truck had 200k on the stock location about the pmd box. ive worked on 2 other ones and ended up giving one away after we couldnt figure out what was wrong with it. the engine had a chance to warm up while we were driving it but not to OT.
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or he could of been totally lying about it stopping once warm just to make the owner feel like it was an easy fix or they could just live with it