any 6.5 gurus here?
 

I just picked up my first 6.5 diesel last week.

1992 3500hd 6.5 turbo with nv4500. truck is a tiltbed car hauler.

I'm not new to diesel (drive a duramax everyday) just the 6.5

from what I read, the early ones (92-93) are the better ones to have, because that's before electronics?

truck runs good, only has 132k miles on it and zero rust.

Here are my 2 issues- hard cold start and oil leaks.

first the oil leaks- I see oil on both driver and pass side of the motor. the only drop that is hitting the ground is coming off the slave cylinder. i know the oil cooler lines need replaced, but not sure what is leaking on pass side? I see an oily film on the tube between the turbo and intake, maybe need to replace the CDR? neither leak is massive, but oil leaks are a pet peeve of mine and I have to fix them

hard start- previous owner told me truck had always been hard to start first start of the day. he bypassed the glow plug controller with a button so he could them in longer. if i get in the truck hold plugs on for 10-15 seconds and crank, truck will fire and sorta chug/run rough for 10-15 seconds, then smooth out. when chugging i get some white-bluish smoke out exhaust, well actually a lot of smoke.
I'm wondering if fuel pump is weak, since tank is in rear it has a long way to pull fuel on the tiltbed truck. or maybe glow plugs need replaced?

Re: any 6.5 gurus here?
 

Check the glow plugs. They do fail. I used to replace them every 3 years or so. Its not hard. Kinda like changing spark plugs. Except for the back 2 on the passenger side underneath the turbo. I always found it easier to go through the wheelwell for those...

Re: any 6.5 gurus here?
 

The oil leak could be coming from a TON of places. Oil drain tube is a common one, but it's it's coming from what looks like between the turbo halves it's likely getting pushed there by crankcase pressure. Not good.

Glow plugs are easy especially if you remove the passenger inner wheel well, but DO NOT BIY CHEAP PARTS STORE ONES. Please buy either Bosch or AcDelco. Also anti-seize is your friend here. Lots of people love the mechanically pump ones, but 94-95 have aftermarket options for a multi position tuner, 96-2000 not do much.

Your fuel pump is actually a lift pump mounted on the driver side frame rail btw, ran off the oil pressure sensor. Those are a common fail point as the wiring gets corroded and will cause finiky issues.

Also pick up a spare pmd to keep on hand, and if it hasn't been done yet I would relocate the current one off the pump.

Re: any 6.5 gurus here?
 

isn't the PMD only on the 94+ electronic trucks? not the mechanical 6.5s?

Re: any 6.5 gurus here?
 

Crap, yea I totally forgot. It's been a looong day lol

Re: any 6.5 gurus here?
 

Did a mini "tune-up" yesterday.

8 new glow plugs (AC delco) new fuel filter, new air filter, and new CDR.

verified lift pump is working when I primed fuel filter. I thought I read somewhere online that the early trucks the lift pump doesn't give the 2-3 second prime like the later trucks? could that be part of my hard start issue? thought I read somewhere of people putting a button in to hit the pump with 12v for a primer?

oil leak unfortunately for me looks like valve covers. Also ordered the aftermarket oil cooler lines.

next step is to get the glow plug controller working again (currently bypassed with a switch).

first start after fuel filter change truck started pretty good. played around a lil and shut it down. maybe hour or 2 later went to start and was like truck fired on 6 cylinder and just chugged white smoke for what seemed like 30 seconds before it caught.

Re: any 6.5 gurus here?
 

It should idle up till warm. I'd look into that. There is a fuel heater that can fail. That's why it's smoking on cold starts. I haven't had my '92 since '14 so getting fuzzy on stuff. The glow plugs you bought can probably take the extra time, but what these trucks came with would burn up from that extra time. I think what you want or 9Gs? Make sure you have good firm clean connections at the plugs. I had bought a bypass manual controller someone was making when I had a lower compression high performance engine. All that did was cause problems. Turns out the glow plug system runs on 9 volts, I think it is, and that switch was putting 12v to the plugs burning them up. Other than that episode, the whole 334k I drove that truck it started great.

If you are losing your fuel prime/air getting in somewhere it will crank a lot to start, naturally. I had an issue with that on an '85 with 6.2. Same engine/different filter/separator. I chased and chased till I discovered the culprit was the base on the filter being cracked...with no replacement available. I could have adapted to the on engine filter from a 6.5 but ended up making up a spin-on fuel filter mount with bleeder using fittings

Re: any 6.5 gurus here?
 

I did put the good AC glow plugs in, this they are 9 or 11gs.

truck does high idle correctly for a few min, then drop down to normal.

I may need to check the fuel heater.

right now, hold the glow plugs in for say 10 seconds, hit the key the truck will fire damn near instantly, but it will run rough and smoke white for a bit. maybe it is the fuel heater.

Re: any 6.5 gurus here?
 

so bumping this back up.

thinking most of my original concerns were just me coming from the dmax not being used to the 6.5

swapped a new glow plug controller on and truck started fine all winter. would grumble a bit if I didnt plug the block heater in when really cold, but always started.

Still havent gotten to the oil leak. fairly sure its the valve covers, so I'm just delaying that job.

Here's the latest issue- truck is hard to restart once its hot. I first notice this issue in april, after roughly 3 hours on the highway, but the problem seems to be worse now that we are into summer.

Heres an example- thursday night run to lowes after work (roughly 30 min drive. cold start at 4 truck is fine. make 2 stops quickly truck is fine.

go into lowes looking for lumber and to get someone to help load, so truck drove 30 min there, and is sitting in hot parking lot- I come out to get in truck, turn key on, no glow plug light, truck chugs for roughly 3-4 seconds and will finally start. I pull up so they can load lumber, shut truck off for maybe 15 min max, same thing on restart, truck cranks for 3-4 seconds before starting.

when it does this, there is NO glow plug light. is that normal? I thought the 6.5 always had a couple seconds of GP no matter what?

is this a sign of a bad injector pump? I've read about pouring water on it to verify, but I never seem to have a water handy when it does this

Re: any 6.5 gurus here?
 

Pair of 6.5’s

Re: any 6.5 gurus here?
 

Carry water with you and try it. That was the exact symptom when my IP was dying. It would crank and not start. Pour a bottle of water over the IP and it would start instantly.

Re: any 6.5 gurus here?
 

yeah since I posted that the truck has continued to do this, and last week I finally had water handy.

yet poured water on and truck fired right up. looking for a rebuilt pump now