Strange cooling problem.

JasonMiller94SC

Registered User
Ok I can't figure this out. I was driving the car yesterday and the temp gauge was reading all the way cold. After about a mile all of a sudden it went all the way hot. I was only a block from home so I pulled in and let it cool off. Today I pulled out the thermostat to make sure it was working properly and it is. I heated some water to 180* and poured it over and and sure enough it opened right up. I put everything back together and let the care idle for 5 minuents. The tempature gauge never moved. I shut it off and checked under the hood. The over flow tank was filling up and when I took the radiator cap off it had plenty of pressure on it. If you put you hand on the pipe comming from the thermostat it was hot, at least 100* but as I moved my hand down the pipe and across the upper radiator hose it was cool. I put my finger in the coolant in the radaitor and it was stone cold. Not a bit warm. When I turned on the heater in the car it blows nothing but cold air. It's like something is blocked in the coolant system but I don't know where. When I filled the radiator it pushed water out the overflow cap that you unscrew from the thermostat housing and if you squeeze the top hose it raises and lowers the amout of coolant in the radiator so the radiator is not blocked. The water pump is only about a year old so it should be good. So it seems I have two problems. The temp gauge is not working and the coolant is not flowing. Any ideas? I'm stumped. :(
 
Hmm, I'm not sure I have anything useful to add.

As I was first reading your posting, I was going to say that a low reading on a temp gauge, and then having it jump to hot, can happen from too low a coolant level. If it's way too low, it will not pump, so the coolant gets hot, but the thermostat and the temp gauge wil not have access to hot coolant. If it does start to pump (from going aroung a corner or something to make ithe coolant hit the pump), you will have hot coolant reaching the temp gauge and can cause what you see.

Us motorcycle guys can get pockets of air in our coolant and have to burp the system to get the hot coolant to hit the thermostat and temp gauge. This usually isn't a problem with cars, but it's cheap to check.

Okay, so as I read on it doesn't seem like that explanation is likely. However, you may want to fill the system through the radiator to give the best cahnce that it's gettign filled.

If you think there's a blockage, remove the thermostat and see if it flows or not. The you can move on from there.

Good luck.
 
Most likely you just have an air pocket. Common causes of air pockets are: Cooling system been recently apart and not completely refilled, defective rad cap, blocked or leaking hose to the reservoir, leak in the system elsewhere, or blown headgaskets.
 
Check the lower radiator hose to make sure it hasn't collapsed. It's the one that gets suction from the water pump and if the hose doesn't have a spring inside, it can collapse causing a loss of coolant circulation and overheating.

David
 
Well I just bought a new radiator cap yesterday so that should be good. I hope to hell it isn't the head gaskests as I just did thoes this spring. I did have a small leak around the thermostat housing so I pulled that apart and put in a new gasket. The hose to the overflow is find as it fills up when the motor gets hot but for some reason the radiator stays cool. Reading my service manual suggests a blocked heater core. Whould that cause this problem?
Is there a way to test the sending unit for the Temp gauge? Maybe that has gone bad?
I was going to get a new thermostat but the guy at the parts store was clueless how to lookup a 180* Tstat and kept telling me that they only had the 195* one that his computer told him I needed. Anyone have a part number for a 180* one or know a car that uses a 180 stock so I can get a new one.
Also the bottom hose has the spring in it and is not sucking shut.
 
Update.
I went out and burped the coolant system again, added just a little more water, and now I can't get the needle to half way. The T stat opens up and the fan comes on and the needle hovers from just below the N up to the O just like it always does. Now, here's the bad part. When I got back from my 3 mile test drive I notice the dreded bubbles comming out of the overflow tank. Are the HG's gone? I just had the heads off this spring and I went ahead and replaced the HG's while they were off. I see no trace of coolant in the oil, or oil in the coolant. Is there a sure fire check to see if the HG's are gone?
 
Next question is, what kind should I get? Morana racing sells a 3 layer gasket. I guess the Felpro's were not up to the task.
 
JasonMiller94SC said:
Update.
I went out and burped the coolant system again, added just a little more water, and now I can't get the needle to half way. The T stat opens up and the fan comes on and the needle hovers from just below the N up to the O just like it always does. Now, here's the bad part. When I got back from my 3 mile test drive I notice the dreded bubbles comming out of the overflow tank. Are the HG's gone? I just had the heads off this spring and I went ahead and replaced the HG's while they were off. I see no trace of coolant in the oil, or oil in the coolant. Is there a sure fire check to see if the HG's are gone?

Jason,

Just because you seeing a few bubbles doesn't mean anything is wrong. That could just be the rest of the air pocket being pushed out. Give it a couple days, if it still bubbles change the cap before doing anything drastic.

David
 
David Neibert said:
Jason,

Just because you seeing a few bubbles doesn't mean anything is wrong. That could just be the rest of the air pocket being pushed out. Give it a couple days, if it still bubbles change the cap before doing anything drastic.

David
do a compression check . look at the plugs when you remove them and notice if any are wet and smell of anti freeze . sounds like compression leaking into cooling jacket . probably HG's or cracked heads . try to drive it if you like, but with air pumped into the cooling jacket , the temp sender will not read properly and you could really overheat the engine and that will cause the heads to crack! check it good ! better safe (with the history of these engines) than sorry!
 
Look for a white ring around your collector at the exhaust manifold. When I worked in the shop a few years ago, we could always tell by puttin it on the lift and if the ring was there, they were gone. I know its not a scientific proven way, but we were 100% on every one. Yours might be there if they were blown before though. I use a pressure tester for some and the chemical test for the ones that the pressure tester does not work on.

Chris
 
huckleberry said:
do a compression check . look at the plugs when you remove them and notice if any are wet and smell of anti freeze . sounds like compression leaking into cooling jacket . probably HG's or cracked heads . try to drive it if you like, but with air pumped into the cooling jacket , the temp sender will not read properly and you could really overheat the engine and that will cause the heads to crack! check it good ! better safe (with the history of these engines) than sorry!

I agree that if you have leaking HGs, then you'll first see exhaust blowing into the coolant. For it to go the other way they have to really be really bad and you would have see smoke out the exhaust and/or a coolant loss.

If you're dumping exhaust gas into the coolant, then the coolant will indeed heat up and the temp gauge and thermostat will respond. So, you really won't overheat without knowing it.

For the same reason, a compression check will usually pass because the HGs will first leak only under ignition, unless they are a complete faillure, which doesn't sound like it. I'm just trying to say that passing a compression check doesn't tell you anything regarding possible HG failures. If it fails it tells you something, but not vise-versa.

Before you do anything drastic, just let the engine warm up while the radiator cap is off and wait until the thermostat opens. Top it off so that you can see the coolant in the radiator while you're watching. Blown HGs will have a stready stream of small bubbles in the coolant. They won't go away as you continue to watch.

I hope this helps.
 
David Neibert said:
Jason,

Just because you seeing a few bubbles doesn't mean anything is wrong. That could just be the rest of the air pocket being pushed out. Give it a couple days, if it still bubbles change the cap before doing anything drastic.

David

I just put a new cap on it two days ago so I'm sure the cap is good. I know overheating the car can cause HG failure and after I had the car tuned and found out my injectors were too small I should have been more careful but I wasn't. I got on it for a few seconds a couple different times and I'm guessing because it was going lean it caused it to heat up, quick.
I'll try pulling the cap and watching for bubbles but as it is now I had a steady stream of bubbles comming out of the overflow tank yesterday. In all my years of owning this car and my previous SC I've never seen bubbles after topping off the radiator and driving it for a few miles.
If I have to pull the heads off anyone recomend a good set of heads to put on it? Mine are opened up some but not much more than just gasket matched.
 
Good information above. In my experience with these cars headgasket leaks can be hard to find.

1) compression test almost never works.
2) pressure test only works on bad cases
3) tailpipe smoke test only works sometimes
4) bubbles in overflow can definitely be caused by air pockets bleeding out so don't take that as conclusive evidence.
5) chemical test is most positive. In your case I'd go ahead with a chemical test.

Other things you can check:

1) Pull plugs and look for abnormalities like greenish scaling or damaged porcelin.
2) Make sure the cooling system is in fact full. I have a funnel that fits snug in the rad neck. I fill the funnel 3/4 full of antifreeze, then burp the hoses until no more bubble show up in funnel. As bubbles come out, antifreeze is sucked in.
3) 180 deg thermostat is same as any 350 Chevy or 302 Ford. That will help you get a 180 thermostat.
4) get a new gauge sending unit. they are cheap and you may have a bad one. Make sure it is making a good connection.
5) If the fan comes on and you don't have a chip to tell it otherwise, the engine is getting up to 220 deg. Even a stock 195 thermostat should be fully open long before that. (remember that the A/C and defrost turn the fan on so make sure they are off if you are trying to figure out how hot the engine is getting.
6) How much pressure is building up in the system? If the upper rad hose it gettting really stiff but the rad is cool that is the surest sign that you have air pockets.
7) if the rad is cool and the upper rad hose is soft then the engine is not getting hot in the first place.
8) if you have access to a temp probe it can be very helpful in these cases. You can measure the temp on both sides of the thermostat as well as in all hoses. Can be a big help.

Regarding head gaskets,

1) you didn't say if the heads were resurfaced when you had it apart. If you headgaskets blew once, if they were leaking, or if the engine has been seriously overheated then they need to be surfaced.
2) Felpro gaskets are ok but they don't like extreme heat. If you've been driving around with air pockets you could have damaged them already.
3)You can't use MLS gaskets without decking the block too which means total dissasembly. Some people have used them without decking the block but I don't see how they could have sealed properly.
4) TTY bolts suck. I've seen a lot of terribly uneven torque using that method. I hope you used ARP studs but if you didn't, then do it next time.

Well, that ought to keep you busy for awhile. :)
 
Where would you suggest getting the chemical test done. Just any local shop or should I go to Ford?
I have had the car tuned by Jerry and the fan does come on at about 180-190.
I didn't have the heads resurfased when I put them back on this spring but the car didn't blow the orginal gaskets and never got over heated so I assumed they were fine. I did use the ARP studs when it went back together.

When I checked it today the water in the radiator was down just a bit so I topped it off and started it up. The water seems to be flowing fine now. As soon as the T stat opened up the radiator warmed right up. I let the fan cycle on and off a couple times and took it for a short trip. When I got back and bubbles had started again. I let it idle for about 5 minuents and they stopped. Took the car for another drive and when I got back, bubbles again. I lifted the pressrure relief on the cap and let just a little pressure into the overflow tank and the bubbles stopped. I assume that as long as no coolant is leading into the oil that the car would be safe to drive, at least to the shop. Also I tried shooting a video of the bubbles in the tank. You can see it here.

Thanks everyone for all the info. If these puppies are blown, should I get a good set of heads for the car or just have mine resurfased? Anyone want to try and set a record of the quickest HG change on an SC?
 
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Headgaskets

I am in the process of changing head gaskets on my 94 SC and bought the fel-pro kit which contains MLS gaskets.You said that you should not use these unless the block is milled.Does fel-pro make two different headgaskets for the SC(MLS and standard).If so than maybe I can return the MLS.I assumed fel-pro only made one gasket type for the SC.
 
From what I know Felpro just started making the MLS gaskets ( I know the guy they sent the prototypes to) and I never heard anything about having to do anything special with them. Dosen't mean you don't have to, I just haven't heard that you do.
 
From what I know Felpro just started making the MLS gaskets ( I know the guy they sent the prototypes to) and I never heard anything about having to do anything special with them. Dosen't mean you don't have to, I just haven't heard that you do.
 
The Felpro gasket set for the SC should not include MLS gaskets. Those gaskets are intended for use on the 4.2 F-150 late model truck motors. They do require a smoother deck surface on the block and heads to work properly.

I know of a few people using them with a block surface that isn't as smooth as it should be (me included). To compensate for the rougher surface I spray the block side of the gaskets with copper spray. I do have the heads decked with a very smooth surface and use APR studs. I also have the heads torqued down a little tighter than the specs call for. Mine are at 100 ft pounds.

David

PS: Felpro makes the MLS gaskets for Ford, but in my area the Ford dealer sells them for less than Autozone does for the Felpro MLS gaskets.
 
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