Hey all just pulled in my driveway and realized my lower radiator hose burst at the spot where it rubs against the frame of the vehicle right after the radiator. (Which doesn't sound right to me) Its an old hose though and I'm going to replace it tonight.

One question I have is what is wrong with my recovery system? The overflow tank hasn't filled since I bought the vehicle, and it did a couple of times when i first bought it but not since then. The motor runs at normal temp and I haven't had any other problems with leaks from all that pressure before, but I know that tank should be filling up. The recovery hose looks ok and I replaced the radiator cap but the overflow tank still doesn't fill. Maybe it was the wrong cap? I was sure I had checked the specs and matched it. Anything else I should check out while the coolant is drained from the system?

 

When you drain it, check for "stop-leak" stuff. Also, maybe check for cracks in the overflow and the radiator for cracks/leaks. Check the overflow tube for blockage too.

 

If you fill the radiator to the top, completely full, when the engine is cool, the recovery tank will fill up, or you will blow a hose or something is going to happen when the engine gets hot. The water expands when it gets hot and has to go somewhere. If you leave a air space in the top of the radiator, then the tank will not fill up.

 

The overflow tank on my 86-300 appears to be just a catch jar-there's no way to fill it, and no matter how much I put in the radiator it always ends up an inch or two down. ~Bill

 

Here's how it works:
When the coolant gets hot it expands and goes into the "expansion tank" (if the radiator is full as it should be). Then when the engine is shut off and the coolant cools it contracts and that creates a vacuum in the coolant system which then draws the coolant back out of the expansion tank. The radiator cap has a valve in it. So first thing, check (or replace, if you don't have a tester) the radiator cap. They are dirt cheap and only last a couple of years.

If there is a leak anywhere in the cooling system the vacuum will not be created and therefore the coolant will not be pulled back out of the expansion tank into the radiator.

The easiest way to check for this is to pressurize the cooling system (with a coolant system tester) and see if any coolant leaks out (it could also be leaking internally in the engine, but the tester will show a drop in pressure so you'll know something is leaking).

Any auto shop can perform these tests for under $50 for you if you don't have the tools.

BTW - if your lower hose is rubbing somewhere and you can't get enough clearance with the new hose installation, cut a piece out of the old hose and wrap it around the new hose in the location where it rubs. Use wire-ties to secure it. This will prevent the next blow out. If nothing appears to be touching with the engine off, check your engine mounts. If they are worn a lot the engine could be rocking enough to cause the rubbing you see.

 

I believe you are correct on this being just a "catch-can" originally. I dug the little plug out of the top of the tank, and with a small funnel I can fill it about half-way full. I found a plastic plug that fit in the hole to act as a "lid".

The radiator cap has to be good and functioning, the hose has to be good AND, the end of the hose inside the tank has to be submerged in the fluid at all times or it won't be sucked back into the radiator.