94LC overheated, topped it back off, runs good, rough idle and even worse in reverse. (1 Viewer)

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T

Titec

Joined
Oct 5, 2023
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Location
Michigan
Got a 94LC inline 6 with 335k on her. Love the truck. Unfortunately it has a once in awhile, I ate up all you coolant occurrence. Happened 2 years ago and caught it just fine. This time after about 7-10 miles down the road, she got pretty hot. Noticed it, pulled over and turned it off. I let her sit for about 40 mins and had a buddy come bring me a gallon of water and I already had the concentrated coolant. While waiting I notice the truck had a noticeable oil leak (like enough to covered a square foot or little more) and coolant sprayed out from I'm assuming the overflow. Anyways, I topped her off (about 2 gallons, she was dry) and drove it a few miles down the Rd to my kiddos mom's house. She drove fine and idled good. Got back and didn't notice any leaks at all. Drove it a it again for another 20 mins, no leaks but had developed a pretty bad idle problem ( it's always done this but not as bad) and even worse idle when in reverse, even when giving it gas, you can tell she just wants to stall.

I'd be amazed if the overheating didn't cause any major damages, I thought she was a goner.

So my question is, what would cause a pretty noticable oil leak when piping hot, when cool the leak goes away?

And two: what could I be facing with the idling problem? ( I have noticed if I played with the mass air flow sensor, it does change the idle)

I appreciate any help you guys can give me, love the truck, truck probably doesn't love me back though 😔
 
Titec said:
Got a 94LC inline 6 with 335k on her. Love the truck. Unfortunately it has a once in awhile, I ate up all you coolant occurrence. Happened 2 years ago and caught it just fine. This time after about 7-10 miles down the road, she got pretty hot. Noticed it, pulled over and turned it off. I let her sit for about 40 mins and had a buddy come bring me a gallon of water and I already had the concentrated coolant. While waiting I notice the truck had a noticeable oil leak (like enough to covered a square foot or little more) and coolant sprayed out from I'm assuming the overflow. Anyways, I topped her off (about 2 gallons, she was dry) and drove it a few miles down the Rd to my kiddos mom's house. She drove fine and idled good. Got back and didn't notice any leaks at all. Drove it a it again for another 20 mins, no leaks but had developed a pretty bad idle problem ( it's always done this but not as bad) and even worse idle when in reverse, even when giving it gas, you can tell she just wants to stall.

I'd be amazed if the overheating didn't cause any major damages, I thought she was a goner.

So my question is, what would cause a pretty noticable oil leak when piping hot, when cool the leak goes away?

And two: what could I be facing with the idling problem? ( I have noticed if I played with the mass air flow sensor, it does change the idle)

I appreciate any help you guys can give me, love the truck, truck probably doesn't love me back though 😔
Click to expand...
Have you checked your coolant for oil, or oil for coolant?
 
Two great minds with but a single thought...
 
Malleus said:
Have you checked your coolant for oil, or oil for coolant?
Click to expand...
I have, both looked good. Just took it to the store not even a mile down the road and it's running like... Crap. Starts up fine, seems to want to idle ok, then just fighting for dear life to keep alive/stalls out. Does ok in high rpms, soon as you let off, rough idle/stalls. Basically I got to drive it with my foot on the gas, braking and all to keep the rpms up so it doesn't stall out.
 
Does it idle well when it's cold, but not when it's warm? If you turn on the A/C, does the idle smooth out?
 
Did you loosen the screws on the AFM (MAF) and tug on the harness?

I sure hope not! $$$$

If it truly got that hot, it could have flexed the valve cover enough to allow oil to drop or push oil out an oil pump seal.

The running rough could be coolant not wanting to burn in the cylinders.

Remove your spark plugs and post pics of the electrodes with them numbered 1-6 and we can help analyze.

While you're in there do a compression and leak down test.
 
BILT4ME said:
Did you loosen the screws on the AFM (MAF) and tug on the harness?

I sure hope not! $$$$

If it truly got that hot, it could have flexed the valve cover enough to allow oil to drop or push oil out an oil pump seal.

The running rough could be coolant not wanting to burn in the cylinders.

Remove your spark plugs and post pics of the electrodes with them numbered 1-6 and we can help analyze.

While you're in there do a compression and leak down test.
Click to expand...
I didn't tug on the harness, nor loosen the screws, just wiggle it and realized it was change the RPMs.

I just got done taking at look at it. Checked all fluids before startup, seem fine. Cranked it over, fired up fine, sounds fine when it's in it high idle after start up, then when it idles down, below 1000-1100 RPMs its fighting to stay alive. I ran the truck to operating temp, got a little better. In park was worse than in Drive. In drive the RPMs were more stable but still had the idling issue. Reverse simply just stalls the truck out, which I could keep it alive if I gas it right away.

The part that gets me, the day it overheated, after cooldown and added more coolant, she drove fine, stalled a few times but would fire right back up and do alright. Day later, later, not so much. The truck always had bad days where it didn't like to idle, at stop sighs/red Lights i would have to keep my foot on the gas to keep it running, most days it would run fine.

I would have to get a buddy over with some tool to do a compression test.
 
So I talked to my brother, who owned the vehicle before I did. He told me when he bought the truck 8 years ago or so, he replaced the plugs but not the wires, the wires are from 98'. Although, I would assume bad wires when give bad performance no matter the RPMs? When fired the truck up today and got it to operating temp, I also reved it up to about 3-4 grand for moment and the truck would handle it good.

I've been looking on this forum about vehicle shaking and stalling in reverse. When the truck overheated, cooled, topped off and drove it my friends house a few miles down the road for me and a few guys to look at it. I did take off the air filter cover, and moved the intake around. Wondering if I possibly cracked the intake tubing...

At this point, I feel like I might be giving too much of the benefit of the doubt... That I didn't fry my engine, and somehow the overheating made a problem that existed beforehand worse. (Random days with rough idle and occasional stalls)

This truck is my DD, hoping I don't have to put my s***y S10 back on the road. But we shall see if that is the case.

I did talk to a buddy and he has access to a compression tester. So, hopefully I can do that here soon, just got some rainy days here in northern Michigan and no garage, so it's nothing but fun and games.

Regardless of the outcome, I appreciate you guys for the help! And give some words of disappointment of me not taking care of the old gal, I deserve it.
 
Again, what about the idle performance? If you answer yes to my question, I'd bet I have an answer.
 
Malleus said:
Again, what about the idle performance? If you answer yes to my question, I'd bet I have an answer.
Click to expand...

It's worse cold than warmed up, haven't tried AC on or off.

But, I did go take another look at it, and yeah... The air intake cleaner tube has a huge crack in it in the valley. Got the part ordered and should be here mid week.

At this point, I think the idle problem is separate from my concerns of it overheating, I believe it always had a hairline crack in it, then I made it worse. So I'm left to replace that part, see if it fixes the idle, then from there, see if I did any major engine damage from it overheating.
 
OK, so duct tape will fix the leaking intake problem for the short term. That's likely your idle problem root cause.

The overheating problem is your headgasket.
 
Malleus said:
OK, so duct tape will fix the leaking intake problem for the short term. That's likely your idle problem root cause.

The overheating problem is your headgasket.
Click to expand...
Thanks for the input, I did that last night. Pug it on this morning and drove into town. Truck ran as it should, checked fluids after a 30 min drive and everything checked out. I might have gotten lucky on this on.

Coolant has always had a mystery leak, it's about a gallon a year and it just surprised me this one after doing some longer drives than usually.

I'm use to subi's, you overheat that block and the head is usually toasted. Time will tell on this one.

Again, appreciate all the help on this forum.
 
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