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Greetings...and problems...

alphadeltaromeo

alphadeltaromeo

Diesel Enthusiast
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Location
GA
First time poster here...hi there :) Mangus580 referred me...

Anyway, just purchased a 1994 2500 6.5 2WD burb last night. Now, on to the issues, where I'm trusting I can get some good input to help me resolve the "challenges".

Overheating
Driving today and noticed after 30 mins that it began to overheat. Pull over and check the level in the overflow tank and it's dry. So, after about 45 mins of opening the valve on the manifold and pouring in 3 gallons (it puked probably 1/2-1 gallon out with all the air burping it out) I felt fairly comfy driving it. I watched the temp religiously through the day. It would hover about 190-200, but more to the 200 range.

What I found interesting was that with the overflow pressure cap off, it looked like it was steaming, but when I put my hand carefully over the "steam", it was rather cool. It apparently was more of a vapor. Any thoughts on what it may be? It took me about 45 mins mins as mentioned to get it fairly full of coolant.

Thoughts?

Stalling
So I've done quite a bit of reading up on the PMD. Previous owner told me he had the IP changed 2-3k miles ago. Coming home from work this evening (35 mile drive) it stalled 5 times. The burb would start to act like there was a fuel problem...jolting back and forth. If I pumped the peddle sometimes it would respond with the peddle and then other times it wouldn't for a few pumps, but then a few more it would respond. Then it would just die. I'd crank it and it would run fine for a few and then back to the same activity. I don't believe the PMD has had work...but while I know I need to get a new remote mount regardless, does the action reflect just a PMD issue or perhaps a lift pump or something else?

Thoughts?

Any input is greatly appreciated. I've had a merc diesel for some time, but never a 6.5. Thanks in advance!

Andy
 
Knowing this will be a request...here it is :) No name yet though...perhaps Bob the Tomato? lol
 

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Sounds kind of like a blown head gasket, pressurizing the coolant while also eating some it.

The stalling could be related, or a PMD, or a lift pump. Do you have an SES light on? You should check if there are any stored codes in the PCM.

There is a diagnostic checklist that will walk you through some of this stuff. Look through the technical library for the checklist, as well as lift pump troubleshooting ( a very good thread to read a few times, the whole thread from start to fininsh ), and the technical library also has how you can check the codes without a reader, look under DTC in the library.
 
The SES light isn't on. Thanks for the input on the technical library...I'll browse that thoroughly. There are a few other post that were referenced when I posted mine that I'm reading through presently. I'll get to the TL right after I finish the threads.

The head gasket seems like a likely culprit with respect to the coolant issue. The vapor just seemed rather strange.
 
The vapor could be unburnt fuel that got pushed into the coolant and evaporated. Kind of like Blowby, but from the coolant instead of the oil.
 
Head gasket is possible, check the upper Rad hose after starting cold. If it gets hard quickly a sign the HG is bad. Seeing as it is new to you I would change the Fuel filter first and then proceed with the check list and definitely start with the lift pump check. I have had PMD problems in the past and "normally" it just dies instantly, usually it doesn't buck and cough first. When you do relocate the PMD make sure to get it out of the engine bay. Welcome and have fun with your Burb.

P.S. If the guys here can't help you with your Burb no one can.:thumbsup:
 
Found cooling issue...

When taking the plastic cover off to examine the PMD, we accidentally pushed on a hose and heard air...inspecting a bit more we found this bad connection. Started the engine and watched the drip, drip, drip of the coolant.

Tomorrow the hose is getting replaced. Recommendation on a new thermostat? I've read that this OEM one activates at 195 degrees...would I be better to get a lower temp TS?

With respect to remote PMD's...recommendations on preferred kits or are they all similar?

Thanks again,

Andy
 

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Additionally, the LP is brand spankin' new from the looks of it and the connector. I think the PO got tired of trying to fix the stalling and such and decided to sell.
 
Mudbath said:
Head gasket is possible, check the upper Rad hose after starting cold. If it gets hard quickly a sign the HG is bad. Seeing as it is new to you I would change the Fuel filter first and then proceed with the check list and definitely start with the lift pump check. I have had PMD problems in the past and "normally" it just dies instantly, usually it doesn't buck and cough first. When you do relocate the PMD make sure to get it out of the engine bay. Welcome and have fun with your Burb.

P.S. If the guys here can't help you with your Burb no one can.:thumbsup:
Click to expand...

Thanks for the welcome!

So, how long should it take for the upper hose to get hard in your reference? I let it run for a few mins and it didn't get hard.
 
Congrats on finding the coolant leak. a few minutes under the hood can be rewarding at times, and other times not so much. That is a common failure item, most people just put a hose barb fitting and heater hose to there.

Check to see if the LP is running while the engine is idling. Details in THIS THREAD the end of that LP and OPS troubleshooting thread I posted a diagram of how to resolve the common OPS failures while also gaining fuel priming during WTS for easier starting. You need to look at all the OBD1 specific guidance, 1994s and earlier are a little different, but the info is there.
 
I guess it would depend on how bad the HG is. A couple minutes should be plenty, but before engine heats up enough to open T Stat. You might also get bubbles in overflow tank when engine running with bad HG.

That coupler is infamous for leaking, hear is a Thread/Poll on removal/replacement that might be helpful. http://www.thetruckstop.us/forum/showthread.php?17581-Quick-Disconnect-Removal-Poll

Lift pump pressure and volume test need to be done. The pump gets its power through Oil Sending Unit when vehicle is running, another fail point.

With T Stat and Oil sending unit, it is advisable to go GM on replacements.

PMD...I went with Heath but there are other venders. Great guy to deal with, bit pricey but great warrantee http://www.heathdiesel.com/T/Chevy-GM/Chevy-9495/PMD-Isolators/
 
Mudbath...link for that thread...would you be so kind as to repost?

Buddy...thanks much again...I'll invest some time on the thread as well.
 
Just an interesting little bit of info I recently found. If you have the 8 lug 2500 model you most likely have one ton rear brakes. They are the 3.5"x13" shoes. I recently was junk yard hopping and found a 93 or 94 2500 8 lug Sub with the one ton brakes. After some researching on line I came to the conclusion that one ton brakes was probably standard on the heavy Subs. The one I found in the yard also had some wheel spacers about 1.5" thick. Somebody else got the spacers, but I pulled the brakes, backing plate to wheel hub.

Don
 
alphadeltaromeo said:
Mudbath...link for that thread...would you be so kind as to repost?

Buddy...thanks much again...I'll invest some time on the thread as well.
Click to expand...


Andy which link do you need? I just tried both and they both worked for me. let me know and I will repost if necessary post again. Bob
 
If you replace the t-stat get an ac delco 195* lower temps hurt mileage.

We have a local PMD Relocation dealer too, get ahold of Burningoil...
 
Ok, so let's assume that the cooling system is working exactly as it should, with a clean RAD...what should normal operating temp be at 65mph on a long drive?
 
190* is the hottest I've seen since replacing exhaust w/ 4" kit. With the stock exhaust I would get up to 210 on long 6% grades under my trucks own weight.
Good looking Burb by the way.
Take it easy removing that "quick disconnect" heater hose fitting.
How far away are you from Sandersville GA? Good source for pieces parts there at Avant's Salvage.
 
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