Evan Adams
Diesel Enthusiast
and im guessing that is a real gm-3 turbo. Also why is the wire on the wastegate?
1993 6.5 problem I've never seen before!
- Thread starter gearhead143
- Start date
tanman_2006
Full Access Member
I wired the wastegate closed while doing testing last time I used it. Was running 26 psi by 2K rpm and had 3:1 Back Pressure:Boost EGT was OUT THE ROOF and climbing fast.
That is a true GM3. If you replace the turbo please dont go back stock! A rebuild kit for a GM3 isnt expensive, to get by I would just rebuild it. No special tools other than an inch# torque wrench and a way to check end play.
My 93 has alot of blowby, looks like a steam engine. I have pulled the gm turbo on and off so much the coupler is junk and the turbo drain doesnt seal perfect
That is a true GM3. If you replace the turbo please dont go back stock! A rebuild kit for a GM3 isnt expensive, to get by I would just rebuild it. No special tools other than an inch# torque wrench and a way to check end play.
My 93 has alot of blowby, looks like a steam engine. I have pulled the gm turbo on and off so much the coupler is junk and the turbo drain doesnt seal perfect
Evan Adams
Diesel Enthusiast
as i dont have the money for a ATT i will probly do a rebuild for now. And if you ever want to get rid of that 93 let me know. Im really wanting to do a 5 speed swap.
Evan Adams
Diesel Enthusiast
also do you know anyone who sells quality rebuild kits?
tanman_2006
Full Access Member
You can pry the 93 out of my cold dead fingers! lol I have a few spare engines but I dont pull one until it fails pretty bad, it has even compression although low and still starts fine. It still passes the water/ vaccum test.
Walt/ssdiesel MIGHT have a kit (as long as his parts are OEM he serves a 6.5L Napa), email Leroy @ leroydiesel and he might could find it, rockauto probably has them, and the GM Dealer can probably get them. I bought mine on Ebay 4 yrs ago and got 5 kits. I dont want to part with the couple I have left.
Evan Adams
Diesel Enthusiast
You don't happen to have any extra nv4500s Laying around do you?
tanman_2006
Full Access Member
I pleed the 5th
Evan Adams
Diesel Enthusiast
I take that as you do but.,.. You don't wan to get rid of them. Lol
tanman_2006
Full Access Member
I have A spare but am running short on spare parts. Might be time to go parts truck shopping. Are you 4x4 or 4x2? The main shafts are different. Also you will need ALOT of parts other than JUST the tranny, easiest thing is to just watch and wait for a parts rig.
gearhead143
Registered User
Sorry I haven't back with any updates. Ive been working long days and weekends and it hasn't left me with much time to work on the truck. I did purchase a MT480 on ebay for $50.00 less the Lumy probes, and it is in great shape. After talking with many friends across the country I found a guy that had two MT161, and two MT160 probes along with a MT95 alignment tool, I got all of them for $56.00 shipped.
I spent today working on IP timing. I was glad I got the alignment tool as the magnetic probe holder was bent, and now is in the correct position. I set up the pump mark aligned with the cover mark and started it, it was hitting pretty hard (Rattling) let it come to full temp and then ran it up to 1400 RPMs timing was at 3* BTDC. After many tries I now have the timing at -3.5* ATDC at 1400 RPMs. The pump mark is now about a 1/8in from the cover mark (passenger side RH of the truck) it sounds good, no smoke, and starts great. Took it out for a drive power seems good, and just a tinge of smoke when I romp on it hard, and then smoke is gone. Under load WOT I get 8lbs boost with the reference line hooked up.
I am going to install a Pyro gauge this week to see how the exhaust temps look under full load.
I am a little lost as to why the timing marks on the IP and cover are so far off to get it to run correctly. I looked at two other 6.5 trucks that run and sound fine and their timing marks are lined up. Could it be something in the IP?
Recap, Injectors rebuilt to 6.5T spec, rebuilt pump tested by DFI Portland OR, New timing gear set, Fuel drained and tank and lines flushed,Fuel filter GM , Cleaned per-chambers, New glow plugs(AC Delco), New glow plug controller.
I spent today working on IP timing. I was glad I got the alignment tool as the magnetic probe holder was bent, and now is in the correct position. I set up the pump mark aligned with the cover mark and started it, it was hitting pretty hard (Rattling) let it come to full temp and then ran it up to 1400 RPMs timing was at 3* BTDC. After many tries I now have the timing at -3.5* ATDC at 1400 RPMs. The pump mark is now about a 1/8in from the cover mark (passenger side RH of the truck) it sounds good, no smoke, and starts great. Took it out for a drive power seems good, and just a tinge of smoke when I romp on it hard, and then smoke is gone. Under load WOT I get 8lbs boost with the reference line hooked up.
I am going to install a Pyro gauge this week to see how the exhaust temps look under full load.
I am a little lost as to why the timing marks on the IP and cover are so far off to get it to run correctly. I looked at two other 6.5 trucks that run and sound fine and their timing marks are lined up. Could it be something in the IP?
Recap, Injectors rebuilt to 6.5T spec, rebuilt pump tested by DFI Portland OR, New timing gear set, Fuel drained and tank and lines flushed,Fuel filter GM , Cleaned per-chambers, New glow plugs(AC Delco), New glow plug controller.
79jasper
Chickenhawk
How far off are we talking?
Maybe timing gears are off a tooth.
Sent from my USCC-C6721 using Tapatalk
Maybe timing gears are off a tooth.
Sent from my USCC-C6721 using Tapatalk
tanman_2006
Full Access Member
Some rebuilt pumps are not rebuilt to the same specs as stock and causes timing issues. Also worn pumps can have odd things happen. You are not too far out of what I would consider an acceptable pump adjustment.
8psi is stock 6.5L setting. If it works then thats great.
8psi is stock 6.5L setting. If it works then thats great.
gearhead143
Registered User
They are on the mark, the timing set was installed and double checked, and the IP drive gear was installed X to dot and doubled checked before the cover was installed. As I said the IP and cover marks are about a 1/8in offset to the right.
I agree on the pump rebuild and specs, but this one is the first Ive seen this fare off. I did call the shop that rebuilt the pump in the beginning and they said they don't make mistakes like that. I could pull the IP and have DFI tear it down to confirm its a IP problem, but since I was able to get the timing where it is, and stable, I'm going to leave it there till I get the Pyro installed this week.
Interesting thing, I disconnected the boost reference line for a test and when it hit 15lbs I backed out.I only tried this one time. The thing that worries me it the shop that did the IP, injectors, and turbo, disconnected the boost reference line and told him this would fix the smoking problem. I hope the head gaskets live now. There is no excessive pressure in the cooling system and it runs at 180* so I guess time will tell.
tanman_2006
Full Access Member
The way the boost reference on your turbo works is, there is a spring in the boost canister that keeps the waste gate closed until the boost overcomes the spring.
Once you pull the boost reference the waste gate is locked shut. 15psi isn't a big problem but 15 psi is higher than I would run on that turbo on a regular basis. I've ran 20psi and the engine is still alive.
Source Unknown
Once you pull the boost reference the waste gate is locked shut. 15psi isn't a big problem but 15 psi is higher than I would run on that turbo on a regular basis. I've ran 20psi and the engine is still alive.
Source Unknown
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gearhead143
Registered User
Finally had time to install the Pyro. Engine up to temp, Idle 200*, Cruise @35mph 400*, @65mph 600*, and at WOT up to 80mph 825*. I didn't have time to try a WOT run on a 6% grade, or with a loaded trailer. I do just get a wisp of smoke when I slam the throttle down and then its gone. I'm still thinking I should try to get the timing to -4* or -5* as I think this will lower EGTs a little and quiet the engine down a little more.
I was told that Snap-On made a short magnetic probe, does anyone know the PN for this, or know anyone that has a extra one they would sell? This shorter probe sure would make it a lot easier to get it in the holder, the PS pump makes the long probe a pain to get into the holder.
I was told that Snap-On made a short magnetic probe, does anyone know the PN for this, or know anyone that has a extra one they would sell? This shorter probe sure would make it a lot easier to get it in the holder, the PS pump makes the long probe a pain to get into the holder.
