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Okay, am I screwed, and if so, how screwed am I?

normburns

normburns

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Finally got around to doing a little rewiring today for the LP, bypassing the stock wiring, and running straight to the LP. I never did hear the pump operate, and the truck still ran very rough. Power seemed okay, but very rough. While at the shop, it died, and did not want to restart. Chuck shot some break cleaner into the air filter, and it finally did fire, spat out a large cloud of black smoke, ran at about 2300-2400 rpm for a few seconds, and then died again.

My mechanic freely admits that he does not know diesels, but around here, he is all I've got. I may have finally located a diesel mechanic, and depending on the information I read here, I may take the truck to him.

According to my mechanic, he believes that I have a serious problem, maybe even a hole in a piston. Am I right in thinking that is a little premature? He is also thinking that the response to the brake cleaner is an indication of low compression.... THAT one, I just do not "get".

His council is that if it IS a "gone motor", put in a big block. Well, I might be alright with that, if I could find a donor vehicle, so I had everything I needed. The donor would have to be cheap though, because I am operating off savings, not having gotten a regular paycheck in over 3 years. That brings me to the rebuild question. Assuming that I do have compression issues, is this like on a gas engine, where new rings, and bearings, oil and water pumps, and a valve job might not be so out of reach as to be impractical? I was looking at gasket set pricing on ebay, and they did not seem to be outrageous. How does the diesel weight compare to the weight of a big block?

I guess I just need to figure out what is up with the 6.5, before I start planning for a BB. The way my luck has been running though, I am looking.
 
Why not start with pulling the glow plugs and do a compression test?
Some auto parts stores loan the tester or a place like harbor freight sells them cheap.

A runaway from engine oil ingestion is highly unlikely since there is no good way for a piston with a hole in it to share any oil in that cylinder with the others,and it would not be able to ignite any oil with no compression.

I suspect that the brake clean was enough to fire the engine and act like a runaway from over fueling with the brake clean.

Since you did not hear the LP operate even with direct power,there is a good chance that you disturbed a fuel line and air was able to enter the system and the IP lost it's suction and ran out of fuel-hence the no start.

I would advise you to remove the direct power to the LP and do a search here or google for "OPS relay mod" and power the LP that way.
Then get a functional LP and check the lines between the LP and the tank for any holes and repair them.

Once you get fuel to the filter and IP and get the system bled you will likely be good to go.

A few things you could maybe do yourself before resorting to a mechanic who is not familiar with the 6.5.
 
With no sound or vibration coming from the LP even after bypassing the stock wiring that is where I would start. IIRC the last time I bought a LP it was about $75. Are you sure you jumped the pump correctly? If you did and got nothing either your battery is bad, the wires you used are bad or your LP is bad.
 
Or the relay used is bad. Make sure the LP is pumping by opening the t-valve.

Yes, it will run rough till all the air is out.
 
x2 What everyone has said.

The LP is highly suspect, before you can go further you will have to confirm its operation.
 
Here is what just happened: The best thing you did was jump on here for advice.

No lift pump and the engine will not get fuel, period, end of discussion. Some injection pumps have enough suction with an airtight fuel system to run until the next filter change.

Your mechanic must be illiterate or chose to ignore the blue sticker that says do not use starting fluids or immediate engine damage will result. Specifically it could have just blown off or destroyed the glow plugs. The pre-ignition of the 'starting fluid' will eventually or suddenly bend connecting rods. To run that long was a lot of starting fluid help. It stalled because it wasn't getting fuel. I know first hand a 6.5 WILL start and run using only 7 of 8 cylinders. Seen it twice.

You may very well have glow plug debris impacted in the pistons now.

In a case like this you may wish to consult your GM dealer service department as ask them if they have any old school 6.5 diesel mechanics around.

Otherwise there is a lot of info around here and the 6.5 diesel after you learn the in and outs of it is simple enough for use in the military.

A gas guzzling big block is simple. Looking for better information can be done and eventually I hope you find a way to get some use out of your 6.5.
 
WarWagon said:
...the 6.5 diesel, after you learn the in and outs of it, is simple enough for use in the military.
Click to expand...

That almost hurts except it is true and I'm living proof. Makes me think of this one that went around a while back.
View attachment 32706
So War Wagon essentially just said, "The 6.5 Diesel, so easy, a caveman can do it." Too funny:D

Seriously Though, like the other's have said, Confirm LP circuit and LP are good / bad and move on from there.

What I would do:

Correct your wiring to OEM (Do the 94's have the Fuel Pump Prime Circuit red jumper wire at the under hood fuse box like the 96+ do?).

Get under the truck and have someone else key on while you have your hand on the LP.

LP Runs... YES: Suspect Air leaking into the lines. NO: Suspect OPS and or LP.

Disconnect the LP at the frame rail, connect a multi-meter or test probe (lighted) to the wires feeding the LP and KEY ON again.
12 V / light present... YES: suspect LP. NO: OPS very suspect

Jump the LP circuit from inside engine bay (Fuel Pump Prime Circuit) and check for voltage / light again. YES: OPS Bad. NO: Suspect relay switch in the Under Hood Fuse Box?

Reconnect LP and Jump the circuit again, LP runs... YES: Bad OPS. NO: Bad LP and still got a bad OPS.

Anyway, if someone else can chime in and correct me before normburns logs in again, please do.

Schematic attached is actually out of the 97. I do know there are some PCM programming differences between 94 and 97 WRT to the OPS but the wiring diagrams are consistent with what I'm seeing on the 1988-1995 schematics in another manual.
View attachment 32707
 
Thanks for the responses.

Rodd, I checked the wiring to the stock pump, and wired the 12 volts to the "hot" side of the pump. Battery is good, wire and connector are new... sure looks like a bad LP.

JMJNET, no relay in my circuit. I was testing, trying to see if I was right in my thoughts that maybe the stock wiring circuit was bad. I went straight to 12 vdc on the hot side, and ground on the other lead. I have a good relay to use when I figure out the circuit.

Warwagon, OUCH. I didn't know that. If there was a blue sticker, it must have been gone when I got the truck 4 years ago, as I have never seen it. Wish I had!!! SO I guess I need to pull the glow plugs and inspect them to see they are whole? If they aren't, then I probably have a real problem, huh?

Thanks again everyone.
 
A simple ohm test to the terminal of the glow plug will do. 1 ohm give or take is what you want. Open is bad and so is much over 2 ohm depending on rust where you ground your tester. Usually a current test is how they are checked w/o removal from engine and most do not have the tool to do a current test. Check the easy ones and see how they did. Removal can turn into a mess. Use antiseize when installing new or the old ones.

I wouldn't bother ordering a new sticker as they didn't do much to save the engine from starting aids.

The lift pumps last about a year. The OPS, oil pressure switch, burns up often as the contacts can't take the load from the pump. Same unit controls oil pressure gauge that keeps working after the switch is toast. You get 7 volts under load and 12v with the pump disconnected on a burned switch. Lift pump will only run in crank or when the engine oil pressure is up. Some years may run during glow plug - but I would think newer years as my 93 and 95 don't. Use the water drain and a pressure gauge to check lift pump pressure. 5psi or more. This is after the pump is replaced and you purge air from the filter top bleed thumb wheel with lift pump running.
 
On a 1994 you have a lift pump fuse on the passenger side firewall under the cover. There are pictures here someplace. That is an easy place to jumper the lift pump for testing and bleeding. I haven't touched a lift pump in 4 years so they may last a little longer than a year on average.

If the glow plugs have been in over 2 years I would pull them and do a visual inspection as well as continuity test. I'd double check those ohms numbers Should be .02 - .03 ohms. If you have a buzzer on your tester it should be going off.

There are only 2 brands of glow plug to use in these vehicles. I use AcDelco 60G's. If you replace the glow plugs Use only those or Dualtherms? Somebody else verify the 2nd brand. Stay away from all the others - Champion, etc.

Be sure to use High temp anti-seez on the threads when re-installing. I also use copper coat or something on the spade connectors And all other electrical connections

You will also want to do the dual lift pump relay upgrade on a 1994. There is an easy to follow schematic from Buddy here someplace. I prefer to use a relay socket as apposed to plugging the wires into a relay.
 
Wow. Great information. Being a Retired Navy electronics tech, I have DVM's out the gazoo(Fluke, MAC, Blue Point, Ideal, etc. I probably have 20 of the things. I like to keep one in the house, in each vehicle, with each tool box, and a few spares.). I really like the idea of checking the glow plugs by resistance. I can also check by amperage, if that is better, how many amps should be feeding them? I can go up to 10A.

Gauge continues to work, after the OPS is too fried to run the pump... yep, sure sounds familiar.

Thanks again guys. Failing what Warwagon mentioned in his first response, MAYBE I can get by without having to replace/rebuild the engine. I usually favor rebuilding over replacement, unless I get a deal I cannot pass up on a replacement. If I rebuild, I know what I have.
 
A guy can never have to many DVM's.

When doing glow plugs you can clip a lead on the glow plug controler and check at the glow plug spade connector when you have it unhooked for continuity in your wire. Good glow plugs all around doesn't have the same effect if you have a bad wire or 2. Having extra DVM.s helps. It's good to have one with an alligator clip to check the wire and another tester to check the glow plugs.
 
Use only Bosch Duraterms for GP. Second choice is ACDelco 60G (not other part no.).

Other brands will fail prematurely that includes WAP, Champion, Autolite, etc
ACDelco 9G (original stock), 11G will swell.
 
If you stick with a stock replacement style LP,buy AC Delco ONLY and get one for a 93-they have the best pressure and flow available from GM.
 
racer55 said:
If you stick with a stock replacement style LP,buy AC Delco ONLY and get one for a 93-they have the best pressure and flow available from GM.
Click to expand...
X2 on this for sure

I've been sticking with GM or ACDelco for most parts lately. I've had far more failures with aftermarket stuff. Especially electrical parts though
 
Alrighty then. I do not have an adapter that will let my compression tester work. Anybody know where I can get an adapter that will screw into a GP hole, so I can attach the compression tester?

If I have blown this engine, IS there a BB out there that will bolt up to my bellhousing? I have heard a rumor that an older Olds 455 will bolt to it, but have not been able to confirm that. How about the old BB Caddy engines? What were they, 472 and 501? I am tired of "shooting myself in the foot" with the diesel, and at least I know how to work on gas, and how to tune an Edelbrock carb. As it sits, the truck is useless to me. I can't drive it, can't sell it, and it is too heavy to be a paperweight.

My thought is that with an older BB, I lose no power, no torque, and if I keep the same gearing in the tranny, I might even get some acceptable mileage with gas. Yeah, yeah, I know... this is blasphemy, so let the stoning begin.
 
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