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Discussion Starter · #1 ·
Is there any reason I cannot replace the heater hose that is the metal one from the thermostat crossover to the heater core. also does anyone know what size heater hose it takes at the heater core, It looks a little bigger to me..
 

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Is there any reason I cannot replace the heater hose that is the metal one from the thermostat crossover to the heater core. also does anyone know what size heater hose it takes at the heater core, It looks a little bigger to me..
Yes, you can replace the coolant crossover line. Install a barbed fitting and you can use heater hose.
Heater hose size: Heater hose size
 

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Discussion Starter · #3 ·
Yes, you can replace the coolant crossover line. Install a barbed fitting and you can use heater hose.
Heater hose size: Heater hose size
My is leaking at the heater core, so I was wondering if I could run 3/4 hose from the heater to core up to the quick connect, replacing that entire metal line.. I have read that line has to be restricted so it does not blow out the heater core.
 

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Discussion Starter · #5 ·
The coolant pressure from the pressure cap is far more than the coolant pump dynamic pressure. You won't damage a hood heater core.
thank you
 

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I have replaced that heater hose that you are talking about.
The quick connect is replaced with a NPT to barb connector.
I think it is 1/4 inch NPT IIRC, you need to verify.
There is also a GM part no for that part used in old impala.
It should be in the FAQ.
 
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Discussion Starter · #7 ·
I have replaced that heater hose that you are talking about.
The quick connect is replaced with a NPT to barb connector.
I think it is 1/4 inch NPT IIRC, you need to verify.
There is also a GM part no for that part used in old impala.
It should be in the FAQ.
Thank you JMJ I was reading up on it and I kept see things that the hose goes from 3/4 to 5/8 to restrict it so it did not blow out the heater core, but that doesnt make sense to be me because it is an input to the heater core which starts out as 5/8 at the quick connect then goes into a 3/4 hose at the heater core.. I just ordered a new hose made for the truck..
 

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I would not worry about the 5/8" metal tube going into 3/4" hose.
The difference is negligible.
I have changed mine to be like that for more than 15 years now, no issue.

I am not sure if your truck have a rear heater, I have also changed the tee with a 1" Pex tee (fits 3/4" hose nicely).
I soldered a restrictor (using pipe cap) to one of the branch going to the rear heater.
The stock was a plastic/abs which crumple when you try to work on something else.
 

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Discussion Starter · #9 ·
yeah the more I thought about the 5/8 going into a 3/4 end wasnt making much sense as far as being restricted to me.. It is already being restricted coming out of the cross over nipple, so the coolant is going to flow through the 3/4 nicely with no blockage or causing any real additional pressure, Some people make it so complicated when is does not need to be. This is my first Deisel and so far I have done the heads twice, replaced all the injectors and all of that stuff, I had to injection pump replaced wasnt too sure about doing that myself, but I think I could do it now, I have had this thing so far down as to check the timing chain and gears at one point.I think I have changed all the sensors and including the speed sensor on the crank, Water pump, starter and the good Ole PMD driver twice now. Yes I relocated it behind the front bumper too. I think the the only thing I will do is get rid of the bulky air cleaner box, it is always in the way and harder than hell to replace the air filter in it not to mention to get to the battery cables.. Just not sure how I want to go about that yet


I had gotten a new hose but when I went to hook it up to the quick connect the angle in the tubing was off, so I ended going up to the parts store and bought a 5/8 threaded nipple with a 1/2 nipple on it cut a piece of heater hose and used to clamps, got it to slide over the the little ridge on the new hose where the metal is supposed to go through the quick connect plastic piece and no leaks so far, i had my cooling system pressure tester on it for about 30 minutes while I cleaned up tools and such, it never went down, ran it until it hit temperature and I noticed my Egr valve gasket was leaking and not leaks still. I will replace that gasket today and let it run more to check coolant level once again then off for a test beat.. I read so many articles on replacing that quick connect and they were all saying to use a 1/2 pipe threaded nipple with a 1/2 hose nipple and the it fit the heater hose perfectly, well I found out the hard way it the threaded end is a 5/8 threaded end..

Thanks for all your help JMJ I really do appreciate it
 

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The threaded end is 1/2" npt.
It measures about 5/8" on the outside.
5/8" pipe thread does not exist.
 

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Discussion Starter · #11 ·
The threaded end is 1/2" npt.
It measures about 5/8" on the outside.
5/8" pipe thread does not exist.
Well if you put a tape measure up the threads on this thing is says 5/8 to me. The half inch one I bought that everyone is saying is way to small and goes right inside the fricken hole
 

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NPT pipe thread is named by the inside diameter of the pipe.
 

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Discussion Starter · #13 ·
NPT pipe thread is named by the inside diameter of the pipe.
I understand that, but when you are looking for the correct thread size that does not help me,, so when someone says they dont make a 5/8 pipe thread and I went and bought one it causes more confusion as I stated before in this thread..
 

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Discussion Starter · #15 ·
This is the GM part no for 1/2" NPT to Barb connector, just in case you need it:
Well, it is actually Amazon link:
Thank you I got one at O Reilly's seems to be doing good so far drove it like 40 miles yesterday Thank you for all your help JMJnet
 
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You will have one less thing to worry.
 

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Discussion Starter · #17 ·
You will have one less thing to worry.
I am looking at putting a new optimizer 6.5 in it here a 3 or four months not a rebuild but a new from Leroy's Diesel. I have been reading up on some of the upgrades he suggests too. I would rather put 20 thousand into this truck than going out an buying a new one for 60-100 thousand then end up with issues on a used one then the payment of a new one..
 
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If I were you, if the truck runs good, I will drive it and leave it alone.
There is no guarantee that new engine will be even good.
Nothing against Leroy, just a fact that a project of this endeavor has not guaranteed that the truck will be better.
It is not a simple matter of removing an engine and putting a new one.
Knowledge and experience are very important in successful project.
It is up to you, though.

That leaky coolant x-over is a minor issue and everybody have to deal with that in this truck and also the gasser. LOL!!!
 

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Discussion Starter · #19 ·
If I were you, if the truck runs good, I will drive it and leave it alone.
There is no guarantee that new engine will be even good.
Nothing against Leroy, just a fact that a project of this endeavor has not guaranteed that the truck will be better.
It is not a simple matter of removing an engine and putting a new one.
Knowledge and experience are very important in successful project.
It is up to you, though.

That leaky coolant x-over is a minor issue and everybody have to deal with that in this truck and also the gasser. LOL!!!
It is starting to get quite a bit of blow by,, I have used restore in it and it has helped. I am not putting the motor in it. I have a place that did a friend of mines dump trucks and he did a very good job, but before I do anything I will be talking to both Leroy and this other place as well as the mechanic.
 

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My suggestion is to buy the service manual.
I am not sure where to buy it, though.

Read a lot of information (at least 20 years) that is here.
There are a lot of quirks and work arounds in this engine.
 
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