Re: K2500 6.5 turbo Diesel w/troubles !
While I'm fairly new here, and only been aware of 6.5 turbo diesel Injector pump & PMD problems since obtaining my '94 Chevy Suburban, this past August. I made the effort, like every 6.5 turbo engine owner, to understand the workings of their trucks. I did so the first night after driving it home, and getting on the computer to learn as much as I could, even before the PMD started acting up, and I had stalling problems weeks later too.
First let me say, that's a pretty nice Chevy you have there. I'm glad you held on to it, I would of done like wise if it had been my Dad's also.
From your pictures, of the remotely mounted PMD, I would suggest, taking the Aluminum block (heatsink) off, and take it to a local Machine Shop, and have the mill, in 1/4" wide slots, 1-1/8" deep, on the top side between the PMD bolt holes, cut from front to rear, leaving .125" thick fins for cooling, I'm basing that from the picture, and guess of an 1-1/2" thick aluminum block used, would leave a thickness of 3/8" to bolt the PMD to.
From what I've learned about the PMD's online, all the after market producers of relocation kits, say to use grade 5 bolts, torqued to 23 in. lbs, this leads me to the fact that a #10-32 requires 23 in. lbs. and is not a grade 5 machine screw.
I also learned that the owner of SSDiesel, was first to produce a relocation heatsink for the PMD/FSD's and all the others followed suite.
Some diesel machanics, even produced kits to mount the PMD's behind the front bumper, using a 65" to 76" long wiring harness, which adds to the resistance of the current from the ECM, which affects the transistors in the PMD even more, the two 500 watt transistors in the PMD, were by design of Stanadyne's Engineers, choosen for two functions, one to increase the weak signal from the ECM, to a voltage the solenoid needed to actuate the plunger in three positions within the function of the Injector pump. and secondly to heat the side (heavy boss/wall [heatsink] on the side of the pump, to pre-heat the diesel fuel for cold starts. ( One of the threads in this forum, someone found a web site that offered an Army Tech manual, on the 6.5 turbo diesel engins, that had complete tear down and rebuid of the IP, plus Testing and Calibration of same.) I down loaded it, it's a good read! And I learned a little more, than I knew two months ago. One thing was, during calibration after a rebuild, a pump being bolted to the test stand, and all fuel lines bled and connected, the pump was run at 2200 rpms for twenty minutes to warm the fuel, before any adjustments were made. The heat being provided only from the PMD's transistors.
Well son of a gun! Maybe the Engineers at Stanadyne designed it that way, only half the power of the PMD's transistors are required to boost the current for the solenoid to work. Let's think about this for a moment, when the trucks were new in 1994, there were no PMD problems at first, maybe around 50,000 miles, one would go bad!
Or did it? How many times when a truck is serviced, are the four screws to the PMD checked for tightness? Once loosened from 2500 rpms of engine vibrations, will the thermal compound grease be displaced? And not replaced by the service mechanic, because he just did the normal checks, or was hunting down a rattle you heard, after he changed the oil. ??
What about them GM quick-disconnects electrical plugs? How many times have you seen a mechanic, plug and un-plug one to brighten up the connections. ( Stanadyne's new Bullet Proof one has gold pins!) Even they may need to be checked now and again!
I remember a time before the quick-disconnects, when I was about 16 years old, my Dad a master mechanic at the time, was working on our car, checking wires to find a problem, when he pulled a connection full of corrosion and had me run into the house for three or four books of matches, I could not figure out why he wanted them, only to see him tear off the striker strip, and use them to brighten up the brass connectors, attach them and the car started right up, he then wrapped the connection in friction tape ! Who sells that any more?
Whats the Oil pressure switch got to do with the IP or PMD? Well it's in the electrical circuit with the frame fuel lift pump, connected to the lift pump relay, so when and if the engine lost or was low on oil, it would shut off the lift pump, stopping the flow of cooling fuel in the Injector pump that cools the PMD, whereby the PMD overheats and shuts off the IP solenoid, which informs the ECM of low fuel pressure, and the ECM, sends a signal to the Fuel Shut Off solenoid and the engine stalls to prevent a high RPM hunting condition.
One other thing to consider, is since 1997 the U.S. EPA, had determined that we are polluting the atmosphere, and ordered all sulfer be removed from Diesel Fuel, that same Sulfer kept the Optical sensor and internals of the Injector pump working better by the lubrication factor of sulfer, so use a fuel additive with every top off of the fuel tank. Why wait to an eighth of a tank to top off, when under the right climate conditions, water droplets form inside the fuel tank, just waiting to be sucked up and stop a Diesel in it's tracks.
When Stanadyne first produced the DB-4 (DS-4) IP, they told GM's engineers, the IP would work better if not in the engine valley, but a little higher up on the engine, GM needed the service work then, how they needed a bail-out is beyond my understanding, my Grandkids and their children will be paying for that for a long time, after I'm gone.
Which reminds me, my Suburban must be done at the Chevy Dealer, I gotta give them a call to see how much it's going to cost me now!
See Ya All later!
Semper Fi !
Ski
[SIGPIC][/SIGPIC]
'94 Chevy Suburban K2500, 6.5 turbo Diesel, 4X4
'77 Chevy Scottsdale 3/4T PU, 350 V-8, Auto tranny, w/camper shell (my old hunting rig)
'92 Cad. Eldorado 4.9L V-8
'86 Kawasaki Vulcan 750, V-twin
'03 Kawasaki Vulcan 1600 Classic V-twin EFI
Restoration project cars;
'84 Chevy Camaro F41, 350 V-8, TH700R4
'79 Caddy Eldorado 350 V-8,
K2500 6.5 TurboDiesel with troubles.
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Originally Posted by Platina Cruiser
