Is my motor blown?

[DERBINATOR]

I was out in my pasture yesterday idleing around for probably a hour or more. Allof a sudden I could here my raditor overheating and filling the overflow bottle. My gauge read 160 to 170. I turned off the motor andwaited 5 minutes or so for it to quit overflowing and then restarted and it immeditly started overflowing again. I waited another 10 minutes, jumped in and headed for the garage about a 1/4 mile away. It didn't overflow this time but I'm wondering if there was anything left to overflow? This is my guess. Beings the gauge was only at 160-170, I had an air pocket but why? would the thermastat cause this? Or I blew a head gasket or something that is allowing compression into the water circut which then forced the water out? Soryy so long. oh, the motor is a stock 400 with a th350 tranny.

 

[Z3PR]

Do alittle investagating. Pull the dip stick, if the oil has a milky look to it, that's a good indication that it might be a head gasket. What's the water level in the raditor ???

 

[Poohbair]

I would probably start by taking the radiator cap off, filling it w/ fluid, getting it warm enough to get the thermostat open and see if you are getting alot of bubbles in the radiator. Check to see if you have water in your oil, and I am assuming that you didn't have a big cloud of white smoke from the tailpipe or you would have mentioned it. Could just have a bad temp guage... get a inexpensive aftermarket gauge and a new sender installed and see what the temp reads.
It is not all that uncommon on a 400, especially if it has been bored, to develop a crack in the cylinder wall between the cylinder and the waterpassage.

 

[DERBINATOR]

I did pull the dipstick and the oil and level looked fine. When the raitor overflowed it never pulled the water from the overflow jug back to the raditor when it cooled so???? I had checked the raditorlevel before I went out. It was down a couple of inches but not bad. I went out and started it this morning and it isn't blowing white smoke. Could of this been some kind of fluke or??
I am suppose to be leaving for dresser, wi. for the memorial trial ride on thursday so I really didn't need this right now.

 

[mofugly13]

I blew a head gasket on my Toyota once, and was geting just what you described, no water in the oil, and the radiator boiling over after the mofo warmed up. I thought something went bad in the cooling system, turned out to be a blown head gasket. I could see "exhaust" in the coolant. It was like little black stringy specs floatin around in there. Donno if this helps. /forums/images/graemlins/dunno.gif

 

[tRustyK5]

They make an exhaust sniffer for the rad, I've never used one though. I make sure the rad is full and fire the thing up with the rad cap off and let it warm up. If the head gasket is gone it might blow exhuast into the coolant and do exactly what you're describing. I had an 89 Merc Sable that did exactly that...

Did you check for leaks and bad hoses yet? If you had a leak somewhere the coolant level would get too low to cool the engine properly. At that point it would puke the coolant that was left as it boiled over. Depending on the coolant level the sender could have been measuring air temp instead of coolant temp. I've had a few cars and truck do that...get a leak somewhere and all of a suddent the heater is blowing cold, the temp guage is lying and the motor is overheating.

It just seems weird that it would blow a head gasket idling around a pasture...

Rene

 

[DERBINATOR]

I went out and filled it full of water, left the cap off and ran it till it seemed good and warm. The outlet hose was hot and the raditor was getting warm. I didn't see any bubbles in the radiator nor was I blowing white smoke like my Sub did when I had a bad head gasket in that. My temp gauge also never moved. So I ran to town and got a new gauge and thermastat. See what these tell me if anything???

 

[Muley]

What about the possibility of the radiator cap being bad. The same symptoms that Rusty, Matt described could happen if the cap is shot. My old 83 Olds desiel did the samething when it blew the head gasket. I could start the car up and watch the overflow level slowly start creeping up till it eventually started to over flow. The only difference is that it sucked the water back in when it cooled.

So it could be the cap, the more I think about it. If the cap is shot, it will not keep the system sealed, which means when the system cools, it will not draw the overflow tank back into the radiator, due to lack of vacuum.

This makes sense to me, how about anyone else?? /forums/images/graemlins/thinking.gif

 

[tRustyK5]

Yeah, plus a bad cap will contribute to overheating. Pressure in the system raises the boiling point of the coolant...lack of pressure means the coolant will boil a lot sooner.

Rene

 

[DERBINATOR]

Well I installed the new temp gauge and thermastat. And while I was doing that I thought of the radiator cap(as muley and trustyk5 did) so I put a differnent radiator cap on also. Went out to the pasture and tried to copy what I was doing yesterday and no problems. I am tempted to put the old cap back on and go out again. peace of mind in knowing what the real problem was. Thanks for the input!!