Cooling system holding pressure, but still disappearing

[Denny]

I mentioned in another thread I had my SHO checked out by a shop today this is the first time in almost three years it has been in a shop. It was weird, but hey I'm only limited in the things I can investigate..

I've been having coolant disappear for a while now. About two times I had to top off the reservoir during winter when the low coolant light was coming on. It also came on a few weeks ago, I topped it off (1/2 gallon) when I did my oil change on Wednesday 4/20. Well the light came on again last night, 4/24. Checked it today, yup, the reservoir is empty. Had the shop pressure check it, it was holding 16PSI they said. Haven't noticed any green spots anywhere I park either which is leaving to believe it's being ingested. However the technician said the oil looked great, in fact brand new(I told him that I do my own oil changes and it was only five days old). He said based on the performance of the car, it's not headgasket related, but he didn't find any leaks anywhere. So where else could I explore now? The rate at which coolant is disappearing seems to be getting quicker and quicker.

 

[Ishodu]

Is the reservoir cracked? Maybe you should take it out and do a good inspection.

 

[SHOslyter485]

It could be leaking somewhere around the engine block, hitting something hot and burning off. Next time you drive at night, keep an eye on the top of the hood, or when you're at a light, crank the vent on when you take off and notice to see if you smell any coolant.

 

[Denny]

Will do both, but if it was leaking around the block, wouldn't it affect the pressure?

 

[Lupo]

My radiator was leaking, but only when the car was cold. Once it heated up, it would not leak anymore. I just replaced my rad for 75$, and problem solved.

 

[Rockledge]

My radiator was leaking, but only when the car was cold. Once it heated up, it would not leak anymore. I just replaced my rad for 75$, and problem solved.

Ford rads are infamous for that very thing. They especially like to leak where the end tanks are crimped to the core. Sometimes they will crack too, just below where the upper hose connects.

Cerrtainly worth looking over, IMO.

 

[Shoaz]

A leak in the upper part of the overflow tank might do that, where it only leaks when warm. Otherwise I'd think it could still be a head gasket. Have you done a compression test?

Let's hope it's what was previously suggested as being either the rad or a leak onto something that vaporizes the coolant.

I'd suggest double checking the water pump, since that can lead to CPS failure as well.

 

[Lorenr]

Radiator

Check the radiator carefully. The end caps are made of plastic and when the hot water from the engine block returns to the radiator, that is where it cracks and leaks.

Radiators are cheap. Check the threads.

 

[Denny]

I will thoroughly look into the radiator. However if there was a leak, I'd see the stream of coolant somewhere on it or the frame right?
I have a compression testor, I've been wanting to do it for a long time on this "new" engine. I'll try to get to that ASAP.

 

[Ishodu]

The rad could also be sealing itself up when its cool. And coolant would really just evaporate off of it and not make it to the ground.

 

[SHOKYLE1]

had a similar problem it was a bad radiator cap when the car heated up the cap would not hold the pressure and it would over flow the resivor tank and lose coolant on the ground while driving. just pressure test the cap.

 

[Denny]

How do you test the cap?

 

[SHO_Driver]

had a similar problem it was a bad radiator cap when the car heated up the cap would not hold the pressure and it would over flow the resivor tank and lose coolant on the ground while driving. just pressure test the cap.

Yep, I had that problem too. Just replaced the cap and it stopped leaking. At first I couldn't find the leak cuz it only happened while driving. Then on a hot day I parked and saw it leaking 10 mins later.

 

[SHOZ123]

My experience was just like Lupo's. When cold it would leak on the drivers side but once the engine got hot the radiator would expand and seal off holding pressure. It would also heat up and the coolant that did leak would evaporate. Check the bottom of the radiator on the drivers side after the car has sat for 12 hours or so. I bet it is wet there.

If it is a new radiator may have the same problem. I put in a new Modine and in the winter it leaked even worse than the old one. So I took it back out and recrimped the tanks with a vise grips. Worked great after that.

 

[Denny]

I checked all around the radiator...no leaks to be found. If I run the car, let it warm up I would be able to see any steam coming out right? Could the coolant also be burning off that drain hose from the reservoir when it gets hot?

 

[JoeHoe_SHO]

I dont know if it was already mentioned, but the cross over tube under the intake manifold could leak, goes from the upper rad hose to waterpump. Their is an o-ring on the water pump side that could leak. Does your temp gauge climb to N and rapidly fall back to a normal operating temp? Just trying to help

 

[Denny]

Ah yes, that's one area I haven't looked at that I should look into. As for the temps, in stop and go driving it can get up to as high as the O, but if I get moving steadily, as in I'm moving for more than five minutes, or get on the freeway, it will be down by the L. Michigan weather has been kinda weird lately. It was up near 80 two weeks ago, then it snowed for almost a week. On the warmer days, it was running hotter, in fact my battery blew its top off at one point.

 

[shoteen95]

Michigan weather has been kinda weird lately. It was up near 80 two weeks ago, then it snowed for almost a week.

yea, i'll vouch for that...crazy MI weather...

if a heater core is starting to leak, will the coolant leak out onto the ground...or does it leak into the interior? derr, i suppose if that were the case, it'd be really obvious to tell from the odor..

have you put any cardboard under the vehicle while it's parked? it's a good way to see all the accidents our cars make when they're sitting still and you can try running the car while it's still cold...and let it warm up to operating temps just to cover the whole "cold-to-warm expansion based leaks"...

if it's a head gasket problem will there be any white smoke coming from the exhaust? or does that only happen if theres a major HG failure..my mother had an 89 LX and when it's gasket blew, it spewed white from the pipe...not to mention leaked all the coolant all over our garage floor.

 

[SHOKYLE1]

you need a tester to test the caps they are the same testers used to pressure cooling systems up. they have adapters that go from the tester to the cap. the are pretty exspensive mine was 140.00 of course caps are cheap you could just replace it and see what happens.

 

[Rockledge]

you need a tester to test the caps they are the same testers used to pressure cooling systems up. they have adapters that go from the tester to the cap. the are pretty exspensive mine was 140.00 of course caps are cheap you could just replace it and see what happens.

You can rent the tester and the adapter at AZ.