intermittent overheating 2h (1 Viewer)

[calen]

Hi Everyone, looked around and never found what I was looking for so here goes. Had this 82 hj47 troopy for a year now. engine temp has been perfect the whole time, but as of recent, it has decided to over heat (or says its over heating) intermittently. normally the gauge reads at the low third mark unless doing a long hill fast it might get up to half way. first thing i noticed was a couple times after a cold start it would get really high past halfway but then drop back down to the normal mark after about 5 mins. it would do this once and a while and figured it just had something to do with it being winter. but now, a few times over the last couple days its climbed up to the red line start mark. and sat there. id pull over, it drops down the 3/4 mark, and wont go lower, but if I leave it running so it doesn't do a rapid cool down, it just raises back up to redline mark, then after 5 mins goes down to 3/4 mark, and goes back and forth. there are times while it says its really hot while idling and the heater that was blowing hot starts blowing cool, even though it says the waters hot.

now, Today, it went to operating temp and stayed there?

I have not done anything to the cooling system since getting it, and i noticed a tiny dribble from a single row of fins in the radiator, so its got some kind of small puncture/leak. like tiny though, not enough to drip or even hardly noticeable, so I assume its not the cause but probably should be addressed soon.

sensor? thermostat? bubble in rad? bad coolant? dont think its the fan clutch as it gets hotter when it moves, but what do I know lol.

any help greatly appreciated

 

[charliemeyer007]

I vote for change the thermostat.

 

[John Smith]

Is your coolant level full? If so, it is most probably the thermostat.

 

[calen]

Is your coolant level full? If so, it is most probably the thermostat.

hope im gonna sound dumb here (not really had any cooling issues in past vehicles) but reservoir is full and when I opened the rad after it had cooled a bit it had preasure but the filler on this rad comes out and up, and there was no fluid in the neck, but cant see in further.

 

[calen]

lol, hope im NOT gonna sound dumb...

 

[mattressking]

There are a lot of options/items to cover.

1. Is overflow reservoir at the correct level when cold/hot?
2. Is upper rad rad hose hot when at operating temp
3. Is lower hose, hot (but not nearly as hot as upper)
4. Does fan clutch lock up and release
5. Did you verify temp sender is working (use FSM)
6. Did you recently add coolant to the engine?
7. Have you checked compression (see FSM)
8. Inspect entire engine bay, underbody for leaks; note where
9. Does heater work in cab?
10. If you turn heater on, does the temp drop and stabilize?

 

[charliemeyer007]

Maybe the radiator cap isn't letting it pull coolant back in when it cools down.

 

[calen]

There are a lot of options/items to cover.

1. Is overflow reservoir at the correct level when cold/hot?
2. Is upper rad rad hose hot when at operating temp
3. Is lower hose, hot (but not nearly as hot as upper)
4. Does fan clutch lock up and release
5. Did you verify temp sender is working (use FSM)
6. Did you recently add coolant to the engine?
7. Have you checked compression (see FSM)
8. Inspect entire engine bay, underbody for leaks; note where
9. Does heater work in cab?
10. If you turn heater on, does the temp drop and stabilize?

1. didn't know there was a correct level for different temps in the reservoir bottle, what are these levels?
2. its hot but doesn't feel crazy
3. haven't touched it, will put hands on it today. if it overheats again.
4. will check today but don't think thats the issue
5. no, just bought a new one and will throw it in today
6. no
7. no, but there are no other strange things going on. starts, and pulls like a champ, doesn't smoke runs great.
8. no cooling leaks that I can see, aside from the aforementioned tiny wet spot on the face of the rad.
9. yup, except like i said before, it was blowing cool the other day even though the water temp said hot.
10. doesn't seem to make a difference.

Thinking sender or thermostat. Ill get a thermostat too just to rule that out.

 

[jmylie]

Not mentioned but remove the cap from the overflow reservoir and is there a tube connected, so when the radiator cools, it can suck coolant back into the radiator.

 

[calen]

Not mentioned but remove the cap from the overflow reservoir and is there a tube connected, so when the radiator cools, it can suck coolant back into the radiator.

yup. stick is present

 

[pb4ugo]

If the coolant is low your operating temps are going to be erratic. Top off the rad. Try to keep track of how much it takes. A leak is a leak, if it's been leaking for a long while the coolant could be low. The system is designed to operate under pressure too. It may or may not be the problem. If you don't check the rad you'll never know.

 

[calen]

If the coolant is low your operating temps are going to be erratic. Top off the rad. Try to keep track of how much it takes. A leak is a leak, if it's been leaking for a long while the coolant could be low. The system is designed to operate under pressure too. It may or may not be the problem. If you don't check the rad you'll never know.

ok, will do, good point. didnt think it could drain enough for that but true I dont know how long its been doing it. Ill do that tonight before I swap in the new sensor and thermostat, just to see if that is all it was. there is pressure in there, as when i opened it up it hissed.

 

[peesalot]

Do you have an infared thermo ? keep it in truck and when/if gauge shows hot, check various spots, radiator, manifold, thermo housing, see if its normal or the gauge isnt lying ?

 

[peesalot]

careful with the thrmo housing bolts, if they wont budge, Dont keep going, there are plenty of posts regarding broken bolts.

 

[1MOA]

I have not done anything to the cooling system since getting it, and i noticed a tiny dribble from a single row of fins in the radiator, so its got some kind of small puncture/leak. like tiny though, not enough to drip or even hardly noticeable, so I assume its not the cause but probably should be addressed soon.



any help greatly appreciated

Fix the radiator before you start throwing parts at it.
Doesn't matter if anything else is broken but if your radiator is leaking it is not going to cool correctly allow air into the cooling system allowing wild fluctuations in temp.
Remove it have it cored and repaired then move forward.

 

[calen]

update: ok, so feeling a little dumb about this but burped the rad tonight and I was able to put at least three litres into it. after that it went right down, took for a spirited ride up some hills and it stayed steady in the low 1/3 mark. I never thought it was low cause the reservoir was good. I tried blowing through the cap/straw and nothing? does that thing have a valve in it?

not gonna celebrate yet till I drive it for a full couple days but feeling like that was the problem.

 

[pb4ugo]

The reservoir won't work correctly with a leak in the system. It will suck or push thru the path of least resistance.

 

[calen]

The reservoir won't work correctly with a leak in the system. It will suck or push thru the path of least resistance.

ok, but is it supposed to freely let air pass through the straw?

 

[pb4ugo]

Not air, coolant.

 

[calen]

Not air, coolant.

ha ha i mean is it clogged if i try to blow through it and I cant? or does it have some kind of valve?