Went to the track, Is it time for a new motor??? Need Your Help!!!

[Blk91stang]

A little backround on my Combo.

130k mile untouched shortblock, cometic headgaskets, ported stock heads with the recommended RA finish for the headgaskets to seal.


Went to the track tonight hoping my new Pro-Motion clutch was going to hold up (Worked Great!). Anyways after my 2nd run, I noticed my temp guage way up. Under the hood my overflow was overflowing and coolant sprayed everywhere. Cool it down, fill it back up, runs great, temp is 175ish steady. Go for another run to see if it does it again. After the run it was way worse than the last one, COOLANT EVERYWHERE! Added water again and thankfully the car seemed fine and went home with no problems.

Besides the spewing of coolant after a full blast run, I also noticed my overflow bubbling even after the car was shut off for 15-20 seconds or so. Car ran 160 degrees all the way home with no signs of failure (Only happens under boost). Also NO oil in the coolant.

I came to the conclusion that ONLY under 10psi of boost, pressure from the combustion chamber is leaking past my headgaskets into my cooling system causing my problem. I contribute this to my 130k block Deck (Prob not 100% flat whereas my shaved heads are).

I had a problem with 2 headgaskets leaking in the past because of this (I believe) and the Cometics seemed to seal it up all last year with no problems.

Anyone else think my assumptions are right? I think I found myself a project for the summer :SNSign:

 

[Blk91stang]

ttt

 

[stangbear427]

I concur. Ripping it apart will definitely tell you something though, I'd think. I'm 95% sure this has nothing to do with it, but just out of curiousity- how's your t-stat? If you're bored, you *may* want to pull it out and seal it back up without it in there, pound on it a little and see if it still overflows. I've seen this happen (rarely) on boosted imports, the t-stat sometimes glitches under the pressure. However, throwing that much boost into a 130K stock block, with this history of previous gasket problems, I think you've already hit it pretty near on the head. Just my $.02

 

[Blk91stang]

My T-Stat is a 180* with 3 holes drilled around it to help bleed air out of the system. My initial thought, still might give it a try, is to just gut the thermostat and install the ring back in to see if the thermostat was my problem. If not than I guess a 331/347 stroker is going to have to take it's place.

I guess I'm kind of surprised my 130k deck held approx. 16:1 compression for about 2 years now with the deck being my only problem (car still runs great which is a shame, only a problem under full boost).

Thank You for your comment!

 

[89white50]

my thermo is sticking, so it will run perfect steady after it ALMOST overheats for like 10 seconds. throws all the coolant out of the overflow, then when it gets hot as hell the thermo's back up thing to open must open cuz then it will run fine the rest of the day. i got a new one, just havent had to time to toss it in.

 

[85_SS_302_Coupe]

Get an aftermarket thermostat that will stay open under hard driving. Also, what kind of cooling do you run? Stock radiator? Might be time to upgrade and your head gaskets might be just fine. Either way a good 3 core radiator couldn't hurt.

 

[Blk91stang]

Yea, my motor has never had a problem cooling before, always stays under 180 degree's even with a completely stock cooling system (new water pump and radiator).

I'm just going to remove the thermostat and give it a shot and see if it happens again. I'll update in a couple hours and let you know how it went!

 

[Blk91stang]

Welp, took it for a couple runs down the highway and same exact thing happened with the gutted thermostat. I'll test my radiator cap but I would think this would happen all the time if that was bad.

So I guess my next question is... Is CHP a good place to get a 347 stroker rotating assembly? Their Street Fighter kit for $900 looks like a steal to me.

 

[stangbear427]

They were one of the first ones to innovate a 347 that didn't suffer from the inherent weaknesses of that particular rod/stroke ratio. These days, I'd say it's six to one/half dozen the others quality-wise, but CHP has probably sold the most 347's.

 

[Blk91stang]

I also noticed CHP gets a good amount of business with their rotating assemblies. I'm trying to get in touch with Rick91GT with hopes he could help me out on what I need.

 

[stangbear427]

I'm thinking of calling him for my upcoming project as well... too many other fires to put out first. 261,000 miles and my 302 just won't quit so I can replace it. Everything else though... Fords. Dammit.

 

[Blk91stang]

I'm thinking of calling him for my upcoming project as well... too many other fires to put out first. 261,000 miles and my 302 just won't quit so I can replace it. Everything else though... Fords. Dammit.

Wanna borrow my supercharger for a couple blasts down the track? That outta take care of that pesky 261k mile shortblock...

 

[stangbear427]

LOL no, thanks. Unfortunately all the money is going into putting out the other fires as well.

 

[Blk91stang]

Upon more examination, my coolant smells like someone filled my radiator with gas. I may do a leakdown but I'm confident i nailed the problem.

Where does one purchase a stock block to start building? The one in my car is 0 deck so I'd rather start with a new stock block and swap shortblocks when the time comes.