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Discussion Starter #1 (Edited)
Hi everyone I'am new here on this board. Good info here all around. I have already done away with one motor from a 96 cougar 3.8. Replaced it. Now i come across another Cat 96 3.8l i got for 500.00 with possible headgasket failure on the way maybe. I want to attemp a head gasket job on this one if it needs it. My ? how much will a compression check and leak down test cost?

Next here are my symtoms-Temp gauge goes to M , fan kicks on needle back below N. After eight miles needle passes M car runs rought, i pull over let her cool before continuing. No oil in coolant, No coolant in oil. Stat been changed and verified opening. Water pump replaced. From a cold start car runs fine as long as i sit on the parking lot. With radiator cap off radiator over flows, then i put the cap back on. At times coolant missing from overflow. Have not heard any dripping or bubbles noises. The heat is fine. A/C fine. What do you guys say? No White smoke either.
 

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If it is a Ford and it is a V6 and it is 3.8 liters, then it is headgaskets.
Just kidding.
I bought a compression tester that did both leak down and compression to diagnose the headgasket failure on my 89 with the 3.8.

The temp gauge would spike, and it would spit out all the antifreeze out of the overflow. I figured it was head gaskets, so I did a yahoo search or whatever was the best back then on "3.8 headgasket" and I was enlightened to say the least. I got 100k or so before it happened. I wasn't gonna pay 1000->1500 to get it fixed, so I worked a couple hours a day after work for 3 days and replaced them.

Main thing that clued me in as to the problem and where was with my particular failure once plug/cylinder was clean as could be, the others had a pretty good amount of carbon. They can fail in many ways and cause different problems. I didn't get oil/water because it failed in a way that allowed antifreeze in one cylinder, but mainly let engine compression force the antifreeze out the overflow. I also got lots of bubbles in the antifreeze in the radiator.
 

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Discussion Starter #3 (Edited)
I heard about the plugs as a sign of failure they or one being clean. When I get a chance this Sunday I'll pull a few to check. Seems like Sunday is my free to work on car day. If i need to replace heads i'll take a month of Sundays to do it, except for having the heads milled. Shops probally not open Sundays. I have a Chilton's and Haynes to help me being i'am not a mechanic. I have no fear of takeing things apart. I'll label everything male female so forth. But deep down i hope its not heads just cooling system problem because this will make a great second Cougar in the stable. BTW do i need get plugs from underneath or is it easier from on top?
 

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Discussion Starter #4
Okay I check plugs, compression, all check okay. took it to shop for their diagnostic. Got codes for egr valve, both o2 sensors. I only change radiator, still gets the needle past m in norm, fan kicks on lowers temp, then needle climbs backup and it continues this way past 3/4 of the gauge. the water pump is new so is thermostat (180). I took the bleed air screw off when refilling new radiator with new coolant. What am I missing?
 

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pressure check the cooling system, flush it thuroughly.

Also, maybe youe temp sendor unit it bad?

-Thomas
 

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Headgaskets are unlikely on 96+ 3.8L's, You can't just automaticly rule it "headgasket blown" like you can with the pre 96'. I would start with the thermostat and make sure ALL the air is burped out of the system.
 

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snap2 said:
But would a bad temp. sensor cause the engine to overheat? The engine is hot.
No, so that probably rules out that idea. Like ranch said, try the thermostat. I'd pull it out and throw it in a pot of boiling water to see if it opens. Thats a good way of testing them.
-Thomas
 

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Discussion Starter #9
Whats' interesting is I can hear the stat pop open and feel the coolant flow through the top hose an then the bottom. Also whats' interesting is as long as in park, won't go past M for 30 minutes. After that put it in drive and needle sways sometime to 3/4 or just beyond while fan is blowing to bring it back down. To bad I already experience blown heads on another engine. Makes this experience scary. Does trapped air cause hot pocket in block?
 

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Discussion Starter #11
Don't know, that a interesting theory. Anyway i just drove 3 miles with AC on low
and it did not overheat. Any thoughs on that? : :mad:
 

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no, the transmission temperature is totally seperate from the engine's. it should in no way affect how the engine operates. Were these 3 miles on a highway, or traveling at 40+mph? Are you sure the fan is kicking on? Maybe your head cracked from the blown headgasket. Did you have them surface checked?
-Thomas
 

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Discussion Starter #13
this happens at city speeds 30-40 mph. The engine that blew was another Cat. engine. This is a different car (97cougar 47,250 miles auto. 3.8v6)
 

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Well, doesn't the transmission share the same radiator that the engine does? If the tranny is running really hot then couldn't this heat be passed to the engine via the radiator? I'm not trying to be a dick, I'm just wondering?
 

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no, the exchanging of heat would be very minimal. They do share the same radiator, but the coolers are seperated enough where it wouldnt really matter, not to that point anyway. And if the transmission were getting that extremely hot, it would be gone instantly. No more transmission. So that is not the problem.
-Thomas
 
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