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Thumping intake, stalling, driveability issues, HELP!

bmxdkj

bmxdkj

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Chelmsford Massachusetts
As the title states, I have a 1999 Chevy, 6.5, PMD Relocated, soot trap removed and other than that the truck is bone stock. Always ran good up until a month ago, turned out to be a bad PMD. Replaced the PMD with a DTECH with a 6 foot extension cable routed infront of the radiator behind the grill. Just over the last week and a half the truck one morning was easy to start, and the very next morning, almost impossible to start. The temperatures between the two mornings were the same. So I suspected the glow plugs. Then just out of the blue last night I started the truck and it has a slight "skip," "thumping" out of the air intake, and low power/stalling issues have come up again. All the basics such as oil and fuel filters have been changed on a regular basis, glow plugs don't have much more mileage on them, maybe 50k or so and same with the injectors and injector pump. The DTECH was replaced today under warranty and the issue isn't resolved. The truck pours out alot of white smoke after start up, which is very unusual since this truck never did that. Also the truck loses power when you step on the throttle from a stop and slowly dies. PLEASE anyone with any ideas please help me out. Thank you everyone!
 
air out the intake sounds like a valve problem but the white smoke sounds like a head gasket. maybe it's blowing compression into another cylinder andpushing it out the intake
 
From what I've been hearing over on Dieselplace it seems to be a bad lifter or retainer? I guess the nylon on them wears out. Looks like I'm pulling the valve covers off this weekend to find the problem. Thank you guys. Next time I'll fill out a diagnostic checklist as well.
 
carefully check the exhaust port temps at exhaust manifolds. You should be able to determine which side has the problem. Tapping noise?? Sounds like a broken rocker arm or lifter or spring on exhaust valve. The old 5.7's would thump if this happened. Usually a rocker arm with them.
 
bmxdkj said:
From what I've been hearing over on Dieselplace it seems to be a bad lifter or retainer? I guess the nylon on them wears out. Looks like I'm pulling the valve covers off this weekend to find the problem. Thank you guys. Next time I'll fill out a diagnostic checklist as well.
Click to expand...

??? those symptoms and that diagnosis aren't congruent. Not that a bad retainer can't result in a shifted rocker, but your problem doesn't sem to be a dead cylinder...

Please fill out the checklist to give us some data to work from... we can sit here all day and toss wild guesses at you, but it sounds like you already got that somewhere else, so we'll try to be a bit more scientific about things, just for variety.

Unless you like randomly changing potentially-related parts until you find the magic combination? A lot of dealerships seem to like that approach...
 
Mine occasionally makes that thumping noise in the intake when it fires up. It's been doing that off and on now for over two years. No broken parts or anything like that, -no misfiring either, -hits on all 8 when it does it, -doesn't matter if it's hot or cold -then disappears as soon as the lifters all get pumped up. It never made any sense to me how it could be a lifter issue though and not be misfiring?????

It's an interesting phenomenon for sure. I figured if it was serious, it wouldn't have made it this far along (2+ years and coming up on 40k miles). It has done it since the rebuild, -and I used all brand new lifters. It isn't a rod bearing or anything like that, -not a sharp enough thump to be that, -and if it was, I am pretty sure it would do it every time, -and that the engine would have let go by now if it was bearing-related. ??????
 
JiFaire said:
??? those symptoms and that diagnosis aren't congruent. Not that a bad retainer can't result in a shifted rocker, but your problem doesn't seem to be a dead cylinder...
Click to expand...

Exactly what I was thinking too. If you have a dead valve, -you have a dead cylinder.....
 
I know the truck doesn't have a dead cylinder, has plenty of power and drives fine. The stalling issue has been solved as the rear fuel pump decided to take a dump the same time the thumping noise started. The rear fuel tank was still full and the front tank ran itself dry, and obviously the fuel gauge read half a tank or so, so when the thumping noise started I automatically assumed the two problems were related, however I was wrong. Go figure right? So no more stalling. However, I will fill out a checklist later on so this problem can be narrowed down. Thank you!
 
I am having the same problem now since it got cold. My Burb thumps for like 3 seconds when I start it up but only when really cold. If I plug it in or it's not that cold it does not do it. WTF ? Truck runs beautiful otherwise. Sounds like a big air compressor for like 3 seconds. Thump thump thump and then fine. I was thinking the balancer or crank pulley but it looks ok.
 
Have you got one bad glow plug or a loose spade??

One cylinder not firing sounds like hell...
 
Not sure. Truck seems to start ok and I have not messed with them yet. I actually bought some Duratherms from Rock Auto but ended up using them in the CUCV.
 
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