Overheating?

[1Kurgan1]

MY van has started over heating the last few days. First I jumped to conclusions that it would be the head gasket. I bought this van about 2 weeks ago and the guy said he replaced the thermostat.

That is why I jumped to that, but I'm starting to think it isn't that. Here's how it works. The van with heat off will probably over heat within 5 minutes. But with heat on probably takes 10-15min, but here's the thing. Once it hit's max temp it vents. And it vents in a metal line under the wiring harness, once it does that, the temp drops back down past half way on the gauge. That metal line must be a hole, but it only leaks when it's at max temp.

I'm thinking maybe thermostat I need to check the upper and lower house to see if one is cool and one is warm.

But the thing I just started thinking it could be is the radiator cap. I know these are suppose to vent, but when? Are they only suppose to vent if something else is wrong with the cooling system? or are they always venting? If they are always then I could easily see it being that.

[detobias]

the "vent" hose coming off the rad right next to the rad cap is sposed to go to the - wait for it - coolant overflow recovery tank

it holds about 1/2 gallon ; if that fills up, THEN it will drain out from the top of the overflow tank

however no coolant should be coming out of that "vent" hose unless the cooling system pressure has exceeded the rating of the Rad cap, usually 16 psi

I would start by swapping rad caps ; then check the Tstat ; make sure you have the "TD 1/16" vent hole" in the Tstat

[NAJ]

Check rad cap and be sure all air is out of the system.
If you did not drill a bleed hole in the top of the t-stat then....
With the engine cold, remove the hex plug in the cylinder head behind the t-stat housing, fill the radiator until the coolant stays level at the top of the opening, reinstall the plug and fill the radiator and overflow tank.

[1Kurgan1]

I didn't put in the t-stat, but it is that, I checked upper and lower hose temps. Bottom hose was cold. Should I get a new t-stat or will the old one be fine? Also it might not have a new t-stat previous owner said he just put one in, well if he didn't drill a hole that was suppose to be drilled shouldn't I notice that right away?

So should I get a new t-stat or salvage old one, and what needs to be done when replacing it?

[NAJ]

Are you overheating without a t-stat installed?
Is the coolant circulating?
May have a clogged radiator.

[EvilcowRoland]

The lower hose should be cooler than the top hose. The system goes radiator > lower hose > water pump > engine > t-stat > upper hose > radiator. Have you checked the actual temperature of the coolant with a gauge other than the stock one? Is your cooling fan coming on? Also, everything NAJ said +1.

[1Kurgan1]

I havent had time to pull the t-stat, it could be a clogged rad, mines rusty, but I'll be replacing that when I do the t-stat.

Yes the lower hose was cooler, I havent checked it with anything but the stock gauge, but judging by the bottom hose being cool, either means t-stat is bad or clogged rad, or both.

So whats the proper way to install a t-stat, and what about drilling a hole?

[crazymadbastard]

the t-stat has an outer ring that you carefully drill a small hole into that way there is always a little bit of coolant pasing through there and also will allow the engine to self-bleed the air out of the system. The hole should be tiny between 1/16-1/32.

[EvilcowRoland]

DDG- Tricks for going fast!

Scroll down a little. It's the first picture.