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Discussion Starter · #1 ·
Hi all,

First time poster. I've been using this forum to help replace the head gasket on my 4.3 1998 s10. I'm not a mechanic by any means but I've got a FSM and time. I've just completed the job and the gaskets appear to be taking.

I thought all was well, but then I found a leak pooling between the intake and passenger side valve cover. I had hoped the valve cover just didn't take, but I replaced that with no results. I spayed soapy water along the lower intake gaskets looking for bubbles. Nothing.

I fired the engine up again the other day with more light and found a leak at the heater hose fitting on the intake. I took a few pictures of it. I can hear air escaping when I squeeze the lower radiator hose. I didn't take a picture of the fitting without the hose attached, but it is rusted pretty bad. Bits of the fitting have fallen off, I can see how it may not seal properly anymore. I'm wanting to be done working on this truck already.

Am I just being a bonehead and missing something?

Can I just rtv or jb weld this?

If I need to replace it, does anyone know the thread size? I think I remember attempting to remove the fitting when I had the intake off, but it wouldn't budge. I read about some folks breaking the fitting trying to remove it.

Side note, the coolant looked similar to oil because of the coolant flush.

tl;dr This heater hose is leaking and I think its because the heater hose fitting has corroded where it seals. Do I need to replace the fitting or am I not sealing it correctly?

Fluid Auto part Gas Automotive tire Electric blue
 

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B4U Task Force Admin
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Looks more like oil than coolant. Get some brake cleaner and clean the area. Give it a little while and check it again.
 

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Discussion Starter · #3 ·
Looks more like oil than coolant. Get some brake cleaner and clean the area. Give it a little while and check it again.
I thought that initially, but this stuff really doesn't feel like oil.

I have thermocure in there which is most certainly producing this dark brown oil color. It chips off though, it doesn't react like oil does. I can also see it literally coming out of the heater hose.
 

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94 4x4,01 Blazer
2001 Blazer 4dr 4wd LT
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have you tried tightening the fitting? or extract it and use some plumbers tape and reinstall.
 

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Been there Done it
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Those nipples are all 1/2 NPT on the threaded end and either 5/8 or 3/4 hose on the hose end. Make sure your hose isn't split or shredded inside. If it is cut off 3/4". The clamp appears over tightened in the pic. Maybe it's shot?
If the nipple won't come out Google has plenty of how to's. Be sure to teflon tape or pipe dope the threads.
Napa has them for $6.50 each.
 

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Discussion Starter · #8 ·
1/2 NPT on the threaded end and either 5/8 or 3/4 hose on the hose end.
Thanks. I wasn't sure, if I can't find it via google/youtube search I'm usually toast. I just replaced both heater hoses and according to a google search it looks like the OD for that hose is 3/4". This fitting is listed as having a 5/8" barbed hose fitting. Should I find one like this that has a 3/4 barb to match the OD of the hose?

There's also this one which is listed on amazon as having ‎3/4" Hose X 1/2" Npt X 1-3/4", but at O'Reily's it's listed as having a 3/4" barb and a 27/32" thread. Part numbers match too.

I bought some permatex sealant with ptfe for some part of the head gasket job. Will that work for the threads of the fitting if it doesn't already come with sealant?

The clamp appears over tightened in the pic. Maybe it's shot?
The clamp is probably over tightened. I thought I would over tighten it with the hopes of sealing properly. Realizing now it doesn't really make sense.

My course of action now is to assume that the barb has rusted and chipped away enough to not form a proper seal. This necessitates replacing the fitting. I'm going to tear back into it in a few hours after I get some other work done. I'll bring the part down to the auto parts store and make sure the threads all match up.
 

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Discussion Starter · #9 ·
Busy week!

Autozone had a generic part that matched the hose diameter and the 1/2 NPT threads. $7.99 I think. Replaced the heater hose fitting in about 15 minutes. Easy to get to with a crescent wrench. Cleaned the threads, applied sealant and let it sit for 24 hours. Started it up and have been driving it all week with no leaks.

Here are a few photos of the old fitting after it was removed and the new one installed. All the gunk on the alternator bracket is the thermocure/rust mixture.

Thanks for the help!
 

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That fitting is a notorious leaker on all 94-98 and probably others. Looks like your finished fixing, but the most common solution is just to remove, inspect, wire wheel the threads and use a good plumbers liquid pipe dope (then give it time to set -- 24 hrs -- before refilling and testing) -- factory uses some sort of pipe dope which eventually fails, hence the issue. Teflon tape is OK, but can often leak if you don't torque the fitting enough and the last thing you want to do is snap off a 25 cent fitting at the back of your manifold.
 
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