GCam

Hey guys, I am looking at buying another 1st gen, it's primary use will be for travel/adventure, on and off road with my family so reliability is my main focus. The truck I am currently looking at already has some things done to it and I wanted your opinions on whether or not the mods are reliable.

HX35 Turbo
12cm or 14cm Exhaust Housing (He didn't sound 100% sure)
4" Exhaust with Straight Through Muffler
Cold Air Intake
M&H Stage 2 Fuel Pin
VE Pump Turned Up 1.5 Turns
90HP Bosch Injectors


The truck has 125,000 miles and these mods were done 8,000 miles ago. For reliability sake, is there anything I should/could keep or should everything be reverted to stock?

Thanks for your input!

oliver foster

If the mods where installed and driven intelligently, they should be fine.
Is there a boost and EGT gauge in the truck?...I sure hope so.
What year is the truck?
Auto or manual? That would be a lot of extra power to expect a stock auto to handle.

If it runs too hot on the EGT gauge you could easily remove the 90 HP injectors, or turn the fuel screw out a little.

I would mostly be worried about how it was driven [and to what temps] by the last owner.

I have many of the same mods on my trucks and feel they are totally reliable. Mine are all 5 speed with aftermarket clutches though and have gauges which I watch carefully.

GCam

Yes, both boost and EGT gauges. The guy seems to know his stuff, he didn't beat the truck up.

1992 with a rebuilt manual transmission.

I will ask him what the temperatures got too and what his clutch is.

If I wanted to guarantee reliability should I remove the injectors and turn the fuel screw out?

oliver foster

I am just concerned that the truck may have more fuel than air to keep itself cool.
If it runs cool enough EGTs doing what you need a truck to do, you should be fine leaving them in.
If you have to back out the throttle hauling firewood [or whatever you haul with your truck] home to keep the temp. safe, I would look into pulling back some of the fuel. I would do this by turning the fuel screw out or swapping in smaller injectors.

u2slow

Nothing unreliable about that stuff. I have basically the same. Maybe even a touch more fuel. 360,000km on the truck, and most of the mods for the last 25,000km.

I've worked the truck quite hard on 33" tires. On the odd occasion (with enough firewood, or heavy tow, climbing highway grades) I have to take my foot out of it a little due to EGTs. 98% of the time its fine. I'm amazed what the stock 13" clutch has been able to do. (Can't say if its original, but its an OE Sachs type.)

I haven't really stress-tested with 35's yet.

EDIT: do check the rear end over. Seems to be an often-neglected compoent, and the cummins really does ask a lot from it. I addressed a number of issues swapping in a Dana 80, but that was after a pair of beaten Dana 70's (one tired, and one expired) on other cummins trucks I have.

GCam

He said he changed oil and “went through” the diffs. What specifically should I confirm with him?

Also, what other mods/upgrades should I look at doing as far as reliability and longevity? I plan on doing RR steering and valve cover venting. KDP has already been done.

GCam

I will follow up to find out about temps, what range am I looking at to be “safe”?

u2slow

Probably not the best idea to take somebody's word on maintenance when you're especially concerned with reliability. I need to 'go through' my own stuff to have any confidence.

Make no mistake... these powertrains are incredibly reliable. I would look at things like battery leads, headlight wiring/switch, ground straps... Dodge electrics tend not to age the best. Look at fixing any leaks it has because they only get worse with time.

oliver foster

I would say if towing or loaded as much as you plan to use the truck you can keep the temps at 1200*F or less that would be safe.
I can see more than that on some of my trucks, but only for very short periods of time. Something like seeing 1450*F on a 2 second blast to past a 18 wheeler on an uphill grade sort of deal.
Seeing 1450*F on the gauge for a couple of minutes would be pushing your luck though.
I don't know what you plan on hauling with your truck, or what the last guy used it for.
With those mods and a heavy trailer behind it, it is possible to get it hot enough to due internal engine damage.

It is very likely that the mods done are plenty safe for a daily driver, but for a heavily laden tow rig in the Mts it could be over fueled.

The temps I am giving are for a PRE turbo EGT probe. The after turbo ones should read much lower to be safe.

u2slow idea of checking the rear axle by dipping you finger in the fluid and looking for glitter after taking it for a short ride is a decent idea as well.

u2slow

Also, taking somebody's word on how hot they run the EGTS...

If you really need to know, you inspect the turbo... for play, melted/wrecked turbine blades, etc.

oliver foster

I agree just asking is not going to get you reliable info.
You can check it out thoroughly and take it for a test drive though.
I am guessing you will need to wait to test max EGTs while it is loaded AFTER you decide to buy it though.
At some point you need to make a decision and pull trigger or not. There are no guarantees on 25 year old used trucks.

I was mostly going into detail on temps so he could decide if he needs to de-tune it a bit after he buys it.

GCam

Of course haha, at least I would know whether or not he knows what he is talking about if he throws out odd numbers!

GCam

So as far as other mods? Anything I should consider?

ofcmarc

Low pressure Piston lift pump.

Midnite

If the truck is regularly driven at high boost/EGT levels, a lot of times the aluminum compressor housing on the turbo will be discolored and look a little yellowish.

Check for axial and radial play in the turbo. If you push/pull on the compressor nut and you feel movement (axial play), that's a sign the turbo isn't in good shape, and can be a good indicator that the truck was run hard. Radial play isn't that big of a deal unless there's a lot of it.

Those pump mods plus the injectors will kill a stock clutch pretty quickly unless he drove it very carefully. Hopefully it's a good aftermarket clutch that's in there now. If you were concerned, you could turn down the full power screw on the pump a quarter or half turn to help ensure you don't do any damage to the clutch. Of course, you won't be able to do anything about damage that's already been done. I wouldn't mess with the injectors--those sound like good ones with a better spray pattern than stock.

Other mods to look for--anything electrical. "Custom" electrical work is normally hugely questionable and at worst can result in a burning truck on the side of the road. I'm **** about my electrical work for good reason. Look for unprotected (bare) wiring that's not stock, unfused connections, poor routing/securing of wiring, etc. I go through tons of zip ties and split loom to protect wiring. Also look for Scotch Lock connectors (google it to see what they look like). I hate those things with a passion. They're used to tap into an existing circuit, but with the normal vibration of the truck and engine, over time they'll break the wire that was tapped into. They're crap and there are so many better options.

Good luck!