Keep bursting rad hoses...

As of late I've bursted open the tiny rad hose that goes to the thermostat 3 times. It's been replaced within the past 2 years and the original lasted from when the truck was built. I just don't get it, I can tow 5Klbs in and out of the mtns while maintaining highway speed in 120* heat but the last 3 times the hose bursted open it's been cold but not too cold and I wasn't even pushing the truck that hard

What can I do to fix this so it doesn't keep happening? It's a 90 XJ RE 4.0

OK, that "tiny rad hose" is actually a heater hose. Since it's got a right-angle bend in it, are you getting a moulded hose with that bend, or are you simply bending a bit of straight hose to fit? If you've got a moulded right angle in there, you want to replace it with a moulded right angle - otherwise, you've got a stress point in the hose, and "Pop!"

For an inelegant, yet effective, solution to the whole wretched heater hose issue, click this link (big pic...)Click me! Click me! This was done on an 88, so the approach should be similar for your 1990. It does entail deleting the heater control valve (haven't worked out an effective replacement just yet,) and you'll have to measure it out yourself, since I don't know where my notes are at the moment. However, this setup has been going for a good four or five years, and I haven't had any trouble. I need to refine it a bit, but I'll get around to that

im courious to know what the pressure is in that line.

also, im assuming that it is on a feed line to the heater core based on your discription. that would lead me to wonder if you have an obstruction in there.

i would recomend a full flush. then fill with normal mixture of antifreeze/h2o save for one gallon of water and use 1 gal of vinegar. that will help to remove a lot of the build up. run that solution for a couple of days of normal use. dont forget to leave the heater on thus allowing the vinegar solution to work at the heater core to free up any debris. then completely flush again, fill as normal.

also, when you say its cold but not too cold, how cold is it exactly. i had a situation where the antifreeze solution was dead and at 20*F it froze my cooling system solid. i ended up blowing a hose off my radiator, and killing a water pump. trying to get all that thawed out after fixing was a pain. the heater core was the last thing to thaw and i was cirtain that i was going to blow one of the lines. thankfuly the only thing that happened was a radiator line overpressurized and popped off its connection.

The last two times it's been arround 30* but the first time it happened it was arround 45ish. The hole that forms is a tiny pinhole just north of the hose clamp but just enough to relieve the pressure causing steam or Prestone fall-out.

The hose is the 90* one and the last two times it happened I just shortened the hose but the 90*(not even 90*) angle was kept.

All 3 times it's happened the heater has been OFF.

1st 2 times I drove the truck intermittendly all day and it happened, but when it happened I stressed the truck a little bit more than previously in the day. 1st time I was on the interstate and coated a car& semi in prestone.

OK - it starts as a pinhole. You hadn't mentioned that...

Check the nipple that the hose is clamped on to - there may be a defect there that is wearing through the hose. Since the housing is just cast aluminum, a minute with sandpaper (240 grit or finer) should solve that problem neatly - but it sounds like a burr of some sort wearing through your hose. Had you mentioned that, it would have been the first thing I'd have mentioned, since I've seen this about three times in 30 years...

Sorry to leave out that tid-bit, gonna check it now.

Zoro said:

Sorry to leave out that tid-bit, gonna check it now.

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There is no such thing as "useless information" when troubleshooting. If it doesn't apply, we can just ignore it. However, it's those little things that can make or break a solution to a problem that's giving you fits...

The flange felt perty smooth, I think the problem this time was from a bad cut I made last time when trying to repair it. The hose was really thin on the back and that's where the hole happened, I shortened it yet again to a thicker part of the hose.

The hose is new as of 2 years ago from the dealer but it's COVERED in AMC logos, never noticed it 'till now...

Thanks again for all the help

Zoro said:

... The hose was really thin on the back and that's where the hole happened, I shortened it yet again to a thicker part of the hose.

The hose is new as of 2 years ago from the dealer but it's COVERED in AMC logos, never noticed it 'till now...

Thanks again for all the help

Click to expand...

ok, stop trying to milk life out of this hose. get a new one!! if not, you already have experienced what will happen again (three times thus far).

remember that ruber hoses rot from the inside out so the Inner Diamiter of the hose now, may not be the same as it was new, thus not fitting correctly.

if you want to avoid a fourpete, get it replaced.

stewie said:

ok, stop trying to milk life out of this hose. get a new one!! if not, you already have experienced what will happen again (three times thus far).

remember that ruber hoses rot from the inside out so the Inner Diamiter of the hose now, may not be the same as it was new, thus not fitting correctly.

if you want to avoid a fourpete, get it replaced.

Click to expand...

I plan on it BUT this is my DD so some red-necking has to be done from time to time to get from point a to point b.

Zoro said:

I plan on it BUT this is my DD so some red-necking has to be done from time to time to get from point a to point b.

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naw, true rednecking would be rigging up a garden hose for the heate hose and a section of fire hose for a radiator hose. hey, that gives me an idea!!:repair: lol

but i guess youll just run it your way until you have the time to fix it. will it hold, probably but not forever.

I have seen people over tighten hose clamps and cut the hose, actually done it myself.

langer1 said:

I have seen people over tighten hose clamps and cut the hose, actually done it myself.

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X2

langer1 said:

I have seen people over tighten hose clamps and cut the hose, actually done it myself.

Click to expand...

That was why I re-used the factory spring clamps.They are not my first choice of clamp type,but on the plastic heater valve at least they will not crush the plastic.
Wayne