01 Jimmy w/a strange coolant leak

[km2002]

01 Jimmy w/a 4.3L Vortec, A/C. When I got this back from the shop after some electrical and suspension problems, within a day or so the temp gauge spiked and the heater blew cold. Checked the overflow, no coolant. Popped the radiator cap, nothing. So I put some coolant into the radiator as well as the overflow. For a few days I was checking and topping off just about every day. Then I went through about a week where every time I checked, the radiator was full and the overflow OK. I'm thinking, maybe whatever seals exist in the system only needed a week or so to get rehydrated, relubricated, or whatever; and now they're fine.

Then tonight as I was getting gas, I saw a stream coming out from the right side of the vehicle, running over what appeared to be a suspension connection of some kind. The overflow was full; the radiator was not. I poured roughly a gallon of coolant into the radiator; no further spill. It took a while for the coolant to circulate before we had heat in the vehicle again; after that I could have roasted a turkey in there. What I'm wondering is, given the apparent location of the leak, what component is probably leaking; and why would it leak intermittently? Any ideas?

Thanks, all.

[MT-2500]

Originally Posted by km2002

01 Jimmy w/a 4.3L Vortec, A/C. When I got this back from the shop after some electrical and suspension problems, within a day or so the temp gauge spiked and the heater blew cold. Checked the overflow, no coolant. Popped the radiator cap, nothing. So I put some coolant into the radiator as well as the overflow. For a few days I was checking and topping off just about every day. Then I went through about a week where every time I checked, the radiator was full and the overflow OK. I'm thinking, maybe whatever seals exist in the system only needed a week or so to get rehydrated, relubricated, or whatever; and now they're fine.

Then tonight as I was getting gas, I saw a stream coming out from the right side of the vehicle, running over what appeared to be a suspension connection of some kind. The overflow was full; the radiator was not. I poured roughly a gallon of coolant into the radiator; no further spill. It took a while for the coolant to circulate before we had heat in the vehicle again; after that I could have roasted a turkey in there. What I'm wondering is, given the apparent location of the leak, what component is probably leaking; and why would it leak intermittently? Any ideas?

Thanks, all.

Driers or pass side?
Leaking from front of engine on side and running down on bottom or floor.

Check intake gasket at front corners.
On drivers side you may have to remove air/ps bracket to see it.

AND ALWAYS CHECK ENGINE OIL FOR COOLANT.

For hard to find leaks add a little coolant dye and put pressure on rad cold and warm and hot.

[km2002]

It appears that for some reason, from time to time, something is forcing coolant out through an overflow tube near the top of the overflow bucket (passenger side near wheel). That begs the question, what could be forcing coolant out through the overflow bucket, especially in a stream?

[MT-2500]

Originally Posted by km2002

It appears that for some reason, from time to time, something is forcing coolant out through an overflow tube near the top of the overflow bucket (passenger side near wheel). That begs the question, what could be forcing coolant out through the overflow bucket, especially in a stream?

Is engine tempt running hot or over 200 degrees?
Or heating up from low coolant level?
Is rad fan working good?
Are you overfillng coolnt tank?
Is pressure tank filler cap in good shape?
Does it heat up to hot real fast on a heavey pull?
Does it only do it on a long idle sitting still?

Have you checked for any other coolant leaks?

[km2002]

Originally Posted by MT-2500

Is engine tempt running hot or over 200 degrees?
Or heating up from low coolant level?
Is rad fan working good?
Are you overfillng coolnt tank?
Is pressure tank filler cap in good shape?
Does it heat up to hot real fast on a heavey pull?
Does it only do it on a long idle sitting still?

Have you checked for any other coolant leaks?

In order:
Generally, no; gauge usually up near 210 (the 12:00 marking), but not over
Coolant level varies, both in rad and in tank
Yes
Not that I can tell; usually don't fill above fill level mark (anything else comes from vehicle)
AFAIK, altho I've never run into a rad whose cap comes off so easily, even when hot (and no, it's not blowing all over me if I pull it hot)
Doesn't seem to heat up real fast under any operating conditions; but what do you mean?
I've only noticed it usually sitting still w/o engine running, strangely; it has done it one other time at idle
Yes; none found. Friend who works on classic roadsters opined leaking head gasket. But not noticing oil in coolant or anything similar.

[MT-2500]

Originally Posted by km2002

In order:
Generally, no; gauge usually up near 210 (the 12:00 marking), but not over
Coolant level varies, both in rad and in tank
Yes
Not that I can tell; usually don't fill above fill level mark (anything else comes from vehicle)
AFAIK, altho I've never run into a rad whose cap comes off so easily, even when hot (and no, it's not blowing all over me if I pull it hot)
Doesn't seem to heat up real fast under any operating conditions; but what do you mean?
I've only noticed it usually sitting still w/o engine running, strangely; it has done it one other time at idle
Yes; none found. Friend who works on classic roadsters opined leaking head gasket. But not noticing oil in coolant or anything similar.

210 is to hot.
Only 2 degrees below boiling point with no pressure on colant system.
I would start with a new rad/coolant cap and new stat.
And make sure fan clutch is working good and rad air flow good and rad clean.

Head gaskets can leak without water in oil.

Is it heats up fast on a long hard pull or heavey foot on gas points to head gasket,

[Rick Norwood]

The right (passenger) side of the truck has 3 major components that can leak. The Overflow Jug, the Heater Hoses and the Heater Core. Here is a fool proof way to find your leak, that is free.

Go to Autozone and borrow (or rent) the Radiator Pressure Tester, They usually loan them for free. It is basically a small hand held Tire Pump with a Radiator Cap and a Pressure Gauge attached to it. When your engine is shut off and cool, remove your radiator cap and attach the Pressure tester to the radiator and pump the pump to the pressure rating of the cap, usually about 15 Lbs. Have a flashlight ready and look for your leak.