. I pressurized radiator to 16 lbs. Told not to go over 20 lbs because it could spout leaks in radiator. I could see no leaks. I go under hood, looked at where water lines go, saw no leaks. Looked at raidiator up top and bottom and in between, very clean.

I got under van looked at lines going to rear heater core. Say no signs of leaks.

I bypassed front heater core, ran car for 15 minutes, thermostat opened up, fans blew. Let engine cool down. Opened cap and water was down 3 inches. I marked overflow bottle prior to taking a ride. It stayed in same place.

I blew air threw hose going from radiator neck to overflow bottle. Air came through to the bottle.

I made observations, by passed front heater core because can't make observation of that area to eliminate that. I checked oil stick and tranny stick, no bubbles, no water, no milky look.

I am so FRUSTRATED. I can't drive it. I don't want to overheat. Please, please, please help me.I keep putting water back in, now i am sure that i am watering down coolant; That is not good.

What can be done?? HELP!

 

The van temperature gauge is just barely below half way marker after warming up. Does that eliminate any idea that air could be trapped in my system somewhere?

 

Check for a leak in the hose from the radiator to the bottle. It might even be the cap. Even though you had air go to the bottle when tested, a leak here could go to the ground and when the engine cools it would draw in air and not fluid from the bottle.

The water pump may only leak with the engine running, but not likely.

 

It appears this website won't let you post direct links so have to do it this way:

Opening post:

I have a '05 G. Caravan with a 3.8L engine, and 125K miles on it. Started having heat problems (intermittent hot/lukewarm/cool/hot again blowing. Replaced the thermostat and water pump. Issue continued. Losing 2 quarts of coolant every time I drive out 15-20 miles trips (each way). No drips under van.

I had the system checked and pressure cleaned at a radiator shop. They suggested it a head gasket or intake manifold coolant leak.

I rented a pressure tester. The system holds 15 PSI for over an hour. The manual says holding for 2 minutes is adequate for 'no major leaks'. Then I used the tester for the INTERNAL LEAK tests, and the needle does not fluctuate with engine hot and running, like a blown head gasket is said to do in the manual.

Even with system full and topped off, the heater core makes squirting/slosh sounds when I gun the engine when the temp is going to HOT, and every time, without fail, every time, once I get the 'squirt or slosh' sound, immediately the heat blows hotter, and the temp gauge DROPS to normal......Then maybe 5 or 10 minutes down the road, I will see the temp gauge FASTLY rising to HOT, then I drop it into Neutral, rev engine to 3K-4K for a few seconds, the heater core sloshes, then tempo gauge drops to normal, and heater output gets hotter.

Ive already flushed the system forward and backwards, including just the heater core. Everything flows well.

Any thoughts? Thanks?

The pressure tester says nothing of testing the INTAKE MANIFOLD for leaks. What would that show on the pressure tester?

Post #4:

Update....I took the van to a shop and they confirmed it was a blown head gasket. No loss in power. No coolant in oil. No white smoke out out tailpipe. But LOTS of exhaust gases were found in coolant. Technician says it DOES happen that way sometimes. I am going to try a bottle of Bar's Leak Head Gasket Repair #1111, and if it works, I may plan to replace the gasket myself (never did it before) in coming summer. Hopefully the Bar's will work....and last until Spring.

 

Link doesn't work for me.

On the '06 model, I have seen the coolant lines to the rear heater core leak. The only way to check them is to pull back the quarter trim and look. They go from metal line to rubber and use the crimps instead of clamps and they leak there. The coolant gets absorbed by the carpet insulation so you really don't notice it.

 

Looks like you caught me in the middle of an edit. I reposted the pertinent thread posts word for word.

Seems odd. I've never run into a website that won't let you posts links to other websites. Not sure if it's this site or the site I'm linking from (dodge talk).

 

Good information gathered from experience. But the guy whose van was diagnosed as head gasket, had over heating issues. nothing like mine.

Thank you. I did look at line going from rubber to metal under the van where rear heat lines go. Saw no leaks. You know i am got a little bit more optimistic. I checked level when cold and the overflow bottle before driving for 20 miles. Go back and the fluid level is same place before leaving, 2.5 inches below the second neck down which would make about 1 inch of fluid missing.

Maybe it improved because I bypassed front heater core and it took a bit to clear air in line which slowed the process of fluid returning to its level. Maybe air vac was in line going from radiator to overflow and i blew air in it to clear something.

I will keep you posted. I will check it again, two more drives. If success i want to hook up heater core again and test fluid levels. If all goes well i want to remove coolant and replace.

Haynes says to remove t-stat and flush, prior. Please explain: How can water pushed through a hose get through the t-stat, (since it not at operating temp) so water can push through the rear lines to heater and return again? I do want to get all coolant out that was sitting in block, as much as possible. Probably 8 qts. right? How many qts of coolant is needed, rear heater core. I'm going to buy 100% coolant and mix it. less money. Need probably 1 gallon of it, to get 10 qts.

 

When the lines go through the floor, they are metal again until they get to the rear heater core. Then there is rubber hose clamped to the lines and to the heater core. This is where they leak, not under the vehicle. You would have to pull back the quarter trim in order to inspect it.

 

[QUOTE=scotter5;2669336]Good information gathered from experience. But the guy whose van was diagnosed as head gasket, had over heating issues. nothing like mine.[QUOTE]

Really just posted it to show that a pressure test isn't the end all to be all test, especially when you can't find an obvious leak. Keep this in your hip pocket if you don't find that smoking gun.

 

I ran it for about 15 miles and no fluid lost in overflow or radiator. Wondering if blowing out the hose going from overflow to radiator had purged air out when I did it.

I will run it tomorrow and check for the final time, if levels are good, I will hook up lines to heater core again in the front (removing the bypass that i did), and see if the levels stay the same.

I will keep in touch for others in future