Engine hurt after overheat

crashnzuk

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Hey guys. My dad got his truck hot over the weekend towing his travel trailer in 110 degree heat and it is hurt. He said the temp got upwards of 240 on the stock gauge once or twice. He had a cranks but no fire condition after stopping at a rest stop. He let it sit for an hour or so and it fired up and away he went. He stopped for the night and finished his trip home the next day without issue. I asked him how the truck is since I have heard, and stressed to him, that these engines do not take well to overheating. He said it starts and runs fine with no noticeable power loss, but it is making a pop or misfire sound out the tailpipe at idle. Im gonna see about doing a compression test when I'm at his house in a couple of weeks. I'm thinking he burnt a valve, what do you guys think? Truck is the. 98 in my sig.
Travis..
 

Black dawg

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I have seen lots of valve sealing issues with these, never a burnt one though, my machine shop always says that the valve was 'warped"?
 

crashnzuk

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Burnt, warped, whatever, they don't seal very well LOL I'm fearing the worst, but I hope it's only a valve. That would be a relatively easy fix. I don't know the history on this engine, but it seems to be a low mileage long block. Sucks that it's hurtin', it was clean, dry, and zero smoke.
Travis..
 

Black dawg

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I was always told burnt and warped were the same thing.

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actually a burnt valve will be missing a piece (cut out just like using a torch) I never examined the valves that my machine shop said were "warped", but I ASSume that the head of the valve was distorted somehow.

And based on my experience, it will need head gaskets shortly anyway. head studs are relatively cheap for these.
 

crashnzuk

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actually a burnt valve will be missing a piece (cut out just like using a torch) I never examined the valves that my machine shop said were "warped", but I ASSume that the head of the valve was distorted somehow.

And based on my experience, it will need head gaskets shortly anyway. head studs are relatively cheap for these.

Are you saying that it will need HGs shortly because of the overheat?
Travis..
 

towcat

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if you are popping through the exhaust, you need to remove the heads and ***** either valves or valve seats(ie. badly cracked heads)
 

Black dawg

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Are you saying that it will need HGs shortly because of the overheat?
Travis..

from what I have seen 230deg+ temps are usually followed by failed gaskets. I guess the bolts just give up, because they usually are not at full torque when I take them apart.
 

crashnzuk

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I'll see the truck this weekend. I'm betting she ain't good. Just have to see how it is and what the old man is willing to do with it.
Travis..
 

crashnzuk

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Alrighty, got some news. I was gonna do the compression test, but when I got there he had already taken it to a shop nearby to be checked. They came back with #8 has little to no compression. My dad didn't tell me what the others were, but definitely one hole is dead. He has the truck back now, they didn't want to do the repair since it would be to costly. They suggested DIY or move on from it. Does it sound pretty reasonable that it would have burnt the valve and not harmed the piston or bore? The truck is 700 miles away from me, so I can't do a tear down myself at the moment. I'm wondering if it might be feasable to throw a set of heads at this thing and have it back to its old self. What do you guys think?
Travis..
 

lindstromjd

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Tear down costs you nothing but time... I recommend taking off the head and seeing what the real damage is before you buy any new parts for it. The worst part of doing head gaskets on a 6.5 is that damned passenger side exhaust manifold. Once you get that thing out of the way, the rest is pretty cake.
 

crashnzuk

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Yeah, it's probably just gonna have to sit until I can get up there again, or until he can trailer down to me.
Travis..
 

Dieselcrawler

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I've had one that was 0 psi on one cyl. the valve itself has a piece of it missing. not burnt off, but broken off.
 

crashnzuk

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^^Did you damage that engine with overheat, or did you get it that way? Just curious as to how durable the pistons are when subjected to such things.
Travis..
 
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