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94 GMC 6.5 TD Question Re- Exhaust Smoke

SMac

SMac

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I'm new to the GM Diesel arena, although pretty familiar with drivetrain overhaul & repair in anything powered with gasoline. Just picked up a 94 GMC C3500 Dually. It has the "F" 6.5 liter, Turbo Diesel Engine. A little history, from the previous owner. This truck started smoking badly after being overheated. The truck was then parked, and left sitting for 3 years, with nearly a full tank of fuel. Fast forward, the oil level in the crankcase was above the mark by about a gallon, and was the consistency of pudding! :rolleyes5: The Coolant level was down nearly 2 gallons as well. Suspecting at minimum, a blown head gasket. I purchased a Chilton Manuel and started reading through these forums, before tearing it apart. Here is the requested info sheet (a great idea BTW)

Problem: Explain your problem in concise language (ie: Cranks but won’t fire). _________After replacing cylinder heads, injectors, glow plugs, filters, & fluids. Will running the engine with 3 year old diesel cause excessive exhaust smoke? Will cetane boost help this issue? or a different additive? or does the fuel need to be drained and fresh fuel added?

Demographics: tell us about your truck and your ambient conditions:

- Year: ___1994___
- Truck model and class (ie: c2500) ____C3500_____
- Automatic or Standard _____Auto_____
- Mileage: (indicate miles or km) ____166,168_____
- Replaced parts and mods (IP, PMD, chip/PCM, TM, injectors etc) ______heads, injectors, glow plugs, remote PMD added, fluids, T-stat_____
- Model: ‘S’ or ‘F’ engine, NA or Turbo, EGR? ______Turbo, non-egr________
- Ambient outside temp: (indicate *C or *F) _____50 degrees F._____
- What fuel are you using? (#1 Diesel, #2 Diesel, Bio, VO, WVO, etc) ____old #1 Diesel?_____
- What fuel additives are you using? _____none______
- Where are you located? _____Sacramento, CA________

General maintenance: inspect and evaluate the condition of each. When were they last changed?
- Air filter ____new_____
- Fuel filter ____new_____
- CDR Valve? _________
- Coolant – last flushed/replaced at ______new_______
- Oil – synthetic/regular, changed at _____new, rotella 15-40______
- Batteries – state of charge, (matched set) replaced at ______new, matched_______
- Battery cables and grounds (removed, cleaned and tightened): ______cleaned & tight________
- Glow Plugs - how many miles on them? ____new_____ What type? ______AC 60g_______
- Injectors - last changed at _______________


History: (Describe how the problem first appeared.)
- What were you doing when it happened? ______unknown________
- How was the truck running fine before this problem appeared? _______unknown______
- Has this problem ever happened before? _________unknown______________
- Describe any related factors that might be part of the problem. _______unknown_______
- Have you checked for DTC (Diagnostic Trouble Codes)? (Y.N) __Y__ And? ___no DTC's stored_____


Diagnostics:

1] Starting:
1a] Does the engine start? ____Y_____
1b] Does the engine crank over? ____Y____
1c] Are your batteries fully charged? ____Y_____
1d] Have you removed, cleaned, and tightened all battery connections? ___Y_____
1e] Does your Wait to Start light come on for a time? How long? _________
1f] Does your glow plug light come on? ____Y_____ For how long? ____10 seconds (cold)_____
1g] Do you see smoke from the exhaust while cranking? What color? ____N____
1h] Does the Service Engine Light Glow during Start/bulb check? ___Y_____

2] Fuel Issues (if not running):
2a] Can you hear your lift pump working? _____Y_______
2b] Do you get a steady flow of fuel from the water drain (T-handle) ? ____Y_____
2c] Loosen the inlet line from the IP – is fuel coming out (Lift Pump on)? _____Y______
2d] Loosen an injector line and crank the engine - does fuel come out? ____Y_____
2e] Do you hear a vacuum (hiss) when you remove the fuel cap? ___________

3] PMD / IP Issues
3a] Location of PMD (on pump, on intake, remote mounted) _____PMD on Intake, added second remote PMD to Radiator support______
3b] Condition of Extension harness (if used) Vendor or Homemade? ____new, vender_____
3c] Condition of grounds / ground wires to IP / PMD. Check Harness. ____clean & secure_____
3d] PMD Make: _____PMD 1 stanadyne w/flat heat sink on intake, PMD 2 w/finned heat sink behind drivers (left) battery on radiator support______
3e] PMD Age: _____PMD 1 unknown, PMD 2 new________

4] Stalling Issues
4a] Do you experience stalling only when hot? ______N/A______
4b] Does it stall under particular circumstances? (ie hit bump, or on accel) __N/A____
4c] Does pouring cool water over the IP seem to help with restarting? ____N/A_____
4d] Is stalling momentary (engine recovers)? ____N/A_____
4e] Does SES light come on when engine hiccups? ____N/A_____
4f] Does cruise control quit working when engine hiccups? _____N/A______
4g] Does re-starting seem to reset engine, restoring cruise and power? ____N/A_____
4h] Changes to dash lights or instruments during stalling events? ____N/A_______

5] Running Issues
5a] On cold start, does upper rad hose get hard before engine warms up? ___No____
5b] Any bubbles or oil film in coolant overflow tank? ___No____
5c] Any white slime on oil surfaces (dipstick, CDR, oil Fill cap)? _____No_____
5d] Excessive white smoke from exhaust on cold start? ____No_____
5e] Excessive black smoke from exhaust under hard acceleration? _____Unknown_____

6] Performance Issues
6a] Do you have gauges (boost, EGT) ? ______No_____
6b] Maximum boost under load? _____Unknown_______
6c] Have you added a performance PCM (reflash) or Chip? ______No________
6d] Have you changed exhaust / downpipe / crossover? _______No_________
6e] Wastegate – mechanical or vacuum (OEM)? ______Vacuum________

7] Temperature-related Issues:
7a] Single or dual thermostats? ______Single______
7b] Have you replaced them lately? Manufacturer of replacements? _____New____
7c] Have you pulled and cleaned Radiator and coolers lately? _____drain/refill_______
7d] Have you replaced the fan clutch? Manufacturer of replacement? ____No, works properly____
7e] (winter) Have you tested your antifreeze? Good to what temp? _____Yes, Minus 25 degrees_____
7f] (winter) Are you using a winter grille cover? _____No______

List and describe any other factors which are not addressed in this checklist. We can’t see, hear, smell, or touch your truck, so the more descriptive information you can give, the more likely it is that somebody can assist you.

____Found & replaced cracked heads with new heads with Felpro gaskets, new injectors, new glow plugs, new boost solenoid. Changed Fuel filter, air filter, oil filter, anti-freeze. Replaced boost hose._____________________________

My main question is will running this engine with 3 year old Diesel cause excessive tail pipe smoke (whitish/grey) The smoke smells of fuel, not antifreeze. Engine has only been run approximately 30 minutes. On short test drive (4 miles) noticed excessive exhaust smoke, oil level has not chenged, not over pressurizing coolant resevoir, level is also unchanged. Thanks in advance SMac :hello:
 
Being overheated there may have been more damage than just the heads, ie: rings. whitish smoke can be from low compression.

I've burnt old fuel with no problems but others have had trouble.
 
clearhose.jpgI'll check fuel pressure. I installed some clear hose, per a few threads read here. One from the filter/seperator to the bleed valve, to observe LP supply.I also used the clear line From the "H" fitting to the IP & fuel return. I have observed some bubbles in the fuel return, but only a couple little bubbles every minute or so. Heres a picture of the layout.
 
any air is bad it will mess with the optic sensor as well as affect how the fuel is injected by the injectors
 
SMac said:
View attachment 31942I'll check fuel pressure. I installed some clear hose, per a few threads read here. One from the filter/seperator to the bleed valve, to observe LP supply.I also used the clear line From the "H" fitting to the IP & fuel return. I have observed some bubbles in the fuel return, but only a couple little bubbles every minute or so. Heres a picture of the layout.
Click to expand...

Clean engine compartment. Can anyone guess what I would say next about something in there?
 
Leroy doesn't like the location of the PMD, and has a solution for it:agreed::D
 
What does the fuel look like and smell like?
I'd drop the tank. 6 months has a nasty bug/alge/etc build up in in the burb I bought. I had to replace the tank, remove the tank sock, and clean out the fuel filter manager, and replace the lift pump.

Bad fuel will smoke like crazy. Low fuel pressure to the IP helps retard timing and cause white smoke.

I would not risk new injectors on old fuel. You have what, $160 worth of old fuel in the tank?

You sure it is hitting on all 8?
 
About the PMD, thats the way it was set up when I got the truck, as stated in the info request form, I have a "New" Stanadyne PMD mounted to a finned aluminum heat sink mounted to the radiatoer support, with the new cable routed next to the existing one. Just incase the PMD gave me trouble. Heres a picture.pmd3.jpg
Secondly, I put about 40 miles on it yesterday, and the smoke finaly cleared up! Its not smoking on start up, maybe a little puff. The smoke seemed a little blueish. I was thinking maybe the exhaust side seal in the turbo. All grounds are fresh & clean. The fuel looks really good, but I have not dropped the tank. Trying to burn it out if possible. The fuel in the clear lines, is very clear. I'll replace the filter/seperator element again, and see what I get. Thanks for the rapid responses everyone!
 
I get blue smoke on start-up that drops all mosquito's around the block dead. Partially air and valve steam seals and the rest is getting the timing advanced via housing pressure. My other one has just a little blue on startup. The IP pressure takes a turn or two to get up to where it needs to be.

The PMD needs to be out of the engine compartment in the front bumper. Heat cycles (The bigger the temp difference/swing the more stress.) and high heat kills them.

Only the filter will tell you what is in the fuel system. After the tank sock plugs the bypass opens and dumps the stuff in the filter. It is two bolts, 4 hoses, and 1 connector to drop the tank and rid yourself of the sock. Not a big job. If your filter gets bad looking soon then you need to drop the tank.
 
SMac said:
About the PMD, thats the way it was set up when I got the truck, as stated in the info request form, I have a "New" Stanadyne PMD mounted to a finned aluminum heat sink mounted to the radiatoer support, with the new cable routed next to the existing one. Just incase the PMD gave me trouble. Heres a picture.View attachment 31994
Secondly, I put about 40 miles on it yesterday, and the smoke finaly cleared up! Its not smoking on start up, maybe a little puff. The smoke seemed a little blueish. I was thinking maybe the exhaust side seal in the turbo. All grounds are fresh & clean. The fuel looks really good, but I have not dropped the tank. Trying to burn it out if possible. The fuel in the clear lines, is very clear. I'll replace the filter/seperator element again, and see what I get. Thanks for the rapid responses everyone!
Click to expand...

Couple problems I see with that install:

1. Heat sink too small. you need mass to draw the heat out and allow it enough time to dissapate.

2. Location leads to a build up of ambient heat. Outside the engine bay is best, but at least not tucked down in that small cavity where it has opportunity to build heat and not shed it

These are aimed towards longevity, not immediate performance goals. A new PMD will survive the heat cycles, just not as many times as one that has less of a temp swing (delta) from off-cold to running-hot....
 
The fuel will burn, I would add powerservice or something for peace of mind but if the fuel filter looks good then dont sweat it.

x2 or 3 or 4 on the PMD. I bought a truck with a slight studder and a heat sync bolted to the intake. I drilled a hole mounted it behind my bumper and got over a year/70K out of the old pmd. It died with 120* summer heat we had and ALOT of corn fields. Just move it, dont argue :thumbsup:

A puff or 2 at start up is normal and a cloud like Warwagon described is normal for some of our worn out beasts...

Blue after recent head work could be from contaminates being burned (something in the cylinder besides fuel burning). Saw that on one of our diesel grain trucks...

Could be timing related if it persists, get the GMTD scan tech for the best 94-95 6.5L specific diagnostic program out there to set timing
 
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