1995, PMD running & heat issues.

[dkveuro]

Hallo folks. smile.gif
..A quick intro'.

Engineer for 45 years. Primarily Mercedes, Volvo and VW diesels.
Built a lot of them over the years....performance and stock.
Some with ceramic crowned pistons and exhaust valves and a lot
with head porting and compression reduction.

Recently exposed to a customers 1995 6.5l with 'auction purchase' syndrome. 210,000 original miles.
He had used 100,000 mile engine installed, complete with axillary equipment. :rolleyes:
It white smokes a lot on cold start and runs rough for 40 seconds.
Slight hesitation/miss at any rpm over 2000 even in 'N' or 'P'.

A few weeks ago I installed a low mileage PMD and this improved the running a lot.
After several test runs and locating and fixing numerous coolant leaks,
the following became obvious............

White smoke, cold star.
Normal warm start, little black smoke.

Engine sounds 'soft' on acceleration.
Will occasionally 'crackle' and sound like my Mercedes/VW engines.
OBD (generic) codes..None.
OBD engine settings. Pump offset: 0.00 (?)
Coolant temperature 193, (New thermostat.)

Have checked fuel flow with engine running...okay.
Wriggle tested all loom connections and key. No change.
The other day, it ran like a champ with gobs of power, loud crackle and no smoke, but to my
horror, revved to 4500 rpm !!!!
It has now returned to normal rpm limits and lower power.

Having no other truck to compare I am not sure what the motor should sound like.
I test ran it the other day in 82 degree temp's and it started bucking and smoking at 70 mph
with occasional loud crackling at 2200 rpm.

Pulled off the I-35 and measured the temperature of the following...

Fuel pump body : 123 F
PMD body : 144 F degrees.
Coolant : 198 F.

My take is, that the Injection Pump does a good job of cooling, being
as the cylinder head temp was 215 F and the valley read 199 F.

If I was engineering this system I would have the PMD on a heat sink inside the
filtered side of the air filter housing.
I think the coolers, heat sinks etc being sold are likely to overheat in heavy traffic,
and high ambient temp's with no air flow, and would be much higher than a pump mounted PMD

I am fitting a new PMD right now and will take it to the GM dealer here to set the TDC offset.
Will let you know what they find as I do not have a Tech to test myself..

Would be very pleased to have your input on this subject and mounting the PMD in the filter housing for air flow at all times engine is running.

Don.

[More Power]

I'd recommend eliminating some of the possible contributors listed on this link (http://www.thedieselpage.com/members/tt99-9.htm), before going further.

Click the colored text. smile.gif

MP

[moondoggie]

Good Day!

I (& others) are mounting our FSD/PMD between the headlight & the battery, drivers-side. This way, the engine doesn't even have to be running for it to be in a fairly cool place. When I get time, I'm going to open up more holes in the sheet metal in this area, allowing even more access to ambient-temp. air.

We'll see how this works...

Blessings!

Brian Johnson, # 5044

[dkveuro]

Originally posted by moondoggie:
Good Day!

I (& others) are mounting our FSD/PMD between the headlight & the battery, drivers-side. This way, the engine doesn't even have to be running for it to be in a fairly cool place.

We'll see how this works...

Blessings!

Brian Johnson, # 5044 Brian....The point is, that there is no positive air floiw until the vehicle is moving. Whilst in traffic or at the shop, the engine will be running in P or N and no forward movement, so, no air flow to cool the PMD.

My thought about in the air filter box seems to cure that issue......Engine running = air flow..Yes ?

Don.

[BobND]

I just made up a unit for a friend... monster, thick, deep finned heat sink, about 5.5" square.

I bought 4 of the heat sink extrusions on ebay for $23.00, and will be making myself one, next, to replace the commercially-made unit I just installed on my intake. I am VERY disappointed with how HOT that intake-mounted unit gets, especially after working the truck for a while, with the intake heating up from the turbo boost. It seems to me it heats up more from the engine and intake heat than from the heat shed by the electronics.

I installed the FSD to the heat sink with silver-bearing computer processor heat sink compound, just like I did with mine a couple of weeks ago.

http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=008465

I mounted the unit behind the LH headlight, with the channels between the fins vertical, to aid in convection cooling. I used 3/4" X 3/4" aluminum angle to mount the heatsink.

I extended to original harness 3 feet by cutting the plug off, and soldering extra wire to the harness.

At idle, with no forced airflow, it gets just warm to the touch. Remember, at idle, or light load, the FSD is not working very hard, as the fuel solenoid duty-cycle is not high.

There is simply no comparison between the temperature of the unit on my '94's intake, and the unit I just made for the friend's '94.

The FSD is working the hardest when the engine is working the hardest, which usually means you're moving, and there should be some airflow coming in around the headlight. While the intake air flow certainly would help, I'm REAL happy with how this unit is working.

[dkveuro]

Originally posted by BobND:
I just made up a unit for a friend... monster, thick, deep finned heat sink, about 5.5" square............................

I am VERY disappointed with how HOT that intake-mounted unit gets, especially after working the truck for a while, with the intake heating up from the turbo boost. It seems to me it heats up more from the engine and intake heat than from the heat shed by the electronics...................
............................
I extended to original harness 3 feet by cutting the plug off, and soldering extra wire to the harness........................................... ..

At idle, with no forced airflow, it gets just warm to the touch. Remember, at idle, or light load, the FSD is not working very hard, as the fuel solenoid duty-cycle is not high...........
I understand the work/heat load rejection....I was thinking about heat sink after a run up the interstate and shutting down for fuel.
As you can see from my first post, I measured the temperature at the pump and PMD.......Ifra-Red Temp' Gun.
Without this imerical test, we can only guess at the heat load, no matter where the PMD is located.

Can you check the temperature on your install ?
After all the horror stories by the "cooler vendors," I was suprised at the temperature of the pump and PMD in a seemingly hostile enviroment. I was sure I was going to measure temperatures of 200 plus degrees F.

GM obviously did know how to suck heat out of the PDM with the pump mount idea.

Don.

[BobND]

I agree with you on the somewhat effective cooling of the factory PMD. My manifold-mounted FSD quickly gets so hot you can't touch the heat sink, and the old unit still on the pump (of course, not heating up from it's electronics) seems cooler to the touch, even in the seemingly high ambient temperature area.

The friend who I made the heat sink and mount for isn't around much, as he farms, and this is a busy time of the year for him, so I don't have a lot of access to his pkup to take temperature readings.

It will be a week or two before I get time to make up a heat sink for mine, and I'll then carry the infra-red thermometer in the truck, and take a series of measurements, and post them.

[moondoggie]

Good Day!

[i]

[dkveuro]

[quote]Originally posted by moondoggie:
[b] Good Day!

[i]

[moondoggie]

Good Day!

I put my FSD in front of the drivers-side battery because I already had the battery out for something else, & I was able to do it in a few minutes with a piece of 1/2" conduit & a couple screws. I think your way is probably much better than what I did, but I didn't consider that way when I did it, & I don't have much spare time for fun projects like changing the location. :(

Blessings!

Brian Johnson, # 5044

[dkveuro]

Well, ladies and gentlemen...I have good news to impart.
After 240 miles this weekend, the 6.5 is alive and well.

However, it was not cheap to get to this point.
As promised though, here is the game play to arrive at a drivable truck.

I installed a FSD/PMD module.
Test drove and much improved.
Cold start still 'white smoke like a mosquito fogger".
Enter my friend Curtis at the GM shop across the road.

His TECH II showed a faulty stepper motor.
They said that at this point they install a new pump at the shop with this fault...$1800.00 !
I obtained a new stepper motor from DELCO DIESEL in OKC for $150.00.
Curtis installed it and TECH II came back with TDC fault. !!!!
He installed a new TDC sensor ($43.20.)
Cranked the motor up and set the TDC offset to GM spec's.... I forgot to ask what that was !!.

I picked up the truck Saturday noon and drove 240 miles over this weekend .
Smooth and no black smoke even when floored.
This Sunday morning I fired it up and very little white smoke which cleared immediatly and idle was perfect from cold thro' warm.
Seems we got ourselves a good motor.

Well, I'm pleased anywho !

Bye.....