Need help! coolant overflow issue

[Stroker5.0]

Need some opinions help on the following problem:

Coolant leaking top of timing chain cover - so I replaced timing chain cover
still had to keep adding coolant. Block is dry all the way around engine except for driver side rear - wet under head - probably head gasket. Car runs great no smoke out the pipes.

New (and main problem) - Past two days started car up to idle in the am while I get the kid ready for school. Come out probably 10min. and Stewart Warner temp gauge reads 220deg. I open the hood and coolant overflow is full and overflowing.
yesterday I blipped the throttle and temp dropped. I can drive around all day and no problems. Has only done it twice in the am when first start up. Thought about thermstat or water pump. If all the coolant is being held in the radiator then doesn't it seem llike the pump is not pumping???

Any help would be greatly appreciated

Thanks

 

[BK_CAULEY]

sounds to me liek the thermostat is sticking and when you blip the throttle the added pressure from the water pump helps release it.

 

[$uperstang]

sounds to me liek the thermostat is sticking and when you blip the throttle the added pressure from the water pump helps release it.

X2

 

[jrichker]

Do a compression test to rule out a blown head gasket.

Only use a compression tester with a screw in adapter for the spark plug hole. The other type leaks too much to get an accurate reading. Your local auto parts store may have a compression tester to rent. If you do mechanic work on your own car on a regular basis, it would be a good tool to add to your collection.

With the engine warmed up, remove all spark plugs and prop the throttle wide open, crank the engine until it the gage reading stops increasing. On a cold engine, it will be hard to tell what's good & what's not. Some of the recent posts have numbers ranging from 140-170 PSI. If the compression is low, squirt some oil in the cylinder and do it again – if it comes up, the rings are worn. There should be no more than 10% difference between cylinders. Use a blow down leak test (puts compressed air inside cylinders) on cylinders that have more than 10% difference.

I generally use a big screwdriver handle stuck in the TB between the butterfly and the TB to prop the throttle open. The plastic is soft enough that it won't damage anything and won't get sucked down the intake either.

A battery charger (not the trickle type) is a good thing to have if you haven't driven the car lately or if you have any doubts about the battery's health. Connect it up while you are cranking the engine and it will help keep the starter cranking at a consistent speed from the first cylinder tested to the last cylinder.

 

[Stroker5.0]

Thanks J for the in depth info. I usually do not have the time to do major stuff myself, Sometimes it's worth paying someone else so I don't have the headaches. Like "Oh **** I broke a bolt" and you look around and find you don't have a second car to go get another one. I will add your info to my tech list though

The 331 motor was put in last Oct. 10:1 compression Talked to my shop today and they said it may be the head gasket and or the head bolt. The bolt is wet and the coolant may be running down the block making it look like a head gasket leak.

The other issue with the coolant overflowing. Yes I agree it looks like the thermostat is sticking. I bought another and went to replace today, but discovered that my newly installed aftermarket timing chain cover flange is slightly thicker than the original stock one, just barely (by a **** hair) keeping me from extracting the one bolt. I dremeled the timing chain cover to get it out to no avail. The bolt is going to have to be cut and a new shorter one put in. See first paragraph.

Anyway I bolted it all back up, filled up the radiator and sure enough it started to overflow. I moved the car back and forth in my driveway and bam, temp went down and thermostat opened. Sooooo it looks like a date with my shop Tue and to do compression test to verify the head gasket leak.

Thanks everyone for their 2 cents. This is a great site. with a lot of info

93 Mustang coupe, 331 Stroker, 10:1 Comp. Eagle crank & rods, SRP pistons, AFR 185 Heads w/HD valve springs, 1.7 Rockers, 24lb inj. 190lph Pump, Cobra Intake, 70mm TB, 76mm MAF, MSD Ignition and coil, Pulleys, Canton 7qt pan, Lakewood struts and shocks, Megabite Jr. Lowers, BBK HD uppers, Sub Frames, no sway bar, Mach 1 Hood, and battery in the trunk and a few other parts.

 

[jrichker]

The lower head bolts go into the water jacket and will seep coolant unless sealant is used on the threads. I use teflon pipe dope, the other alternative is ARP thread sealer.

 

[Stroker5.0]

Well looks like it was the thermostat sticking. Did a pressure test and no leaks from heads, gaskets, bolts etc. will see how it runs tomorrow

Thanks for all the info and suggestions

 

[BlownFiveLiter]

Alright, I just read everything here, and I have a different take. When you blip the throttle, your temp goes down, correct? I'm thinking you have some air in the system and the thermostat is working. You may have a bad thermostat, but even if it's fine, they're cheap enough that I'd just go ahead and replace it anyway. With an air pocket in the system somewhere, when you blip the throttle, the coolant flows at a higher pressure, so it displaces some of the air and you get some cooling again, and the temp goes down. Put your front end on some jackstands so your radiator is the high point in the system and start filling it back up. Do everything you can to try to get the air out of the system, and chances are, your cooling system will be back to normal if your leaks are all sorted out.