I do Beleive I am FUCT

[oneluckypops]

As most are aware I am swapping a vortec motor in my 85 1 ton. Lately it has been fighting me.
It has had a P0300 (random cylinder misfire code), I diagnosed it as the poppetts were leaking. Finally got the money to buy the MFI conversion ($244.81 shipped to my door). Drove to the shop 20 minutes from here spent about an hour replacing it, started the truck and it ran alot better cleared the code and observed the misfire data on the computer. FIXED IT.

Got ready to take it for a drive and noticed my temperature gauge was pegged out, truck was NOT hot, looked at the ECT on the scanner and it was not even close to warm. Jumped out went to the radiator and grabbed the top hose, still cold but TIGHT as hell. Shut the truck off and the pressure imediatly went to the overflow along with all my coolant. I have been trying to convince myself that its just a stuck thermostat, but I just dont think thats what it is, If I was a betting man ide say I get to put new heads on it now.

Opinions from anyone?

 

[crazy4offroad]

Reverse rotation water pump? Damn man I dunno, hope it's something simple.

 

[Joshua8336]

If I was a betting man ide say I get to put new heads on it now.

i'd have to say the same thing, sounds a little to suspicious to be a stuck thermostat, where did the motor come from, how many miles, etc...

 

[oneluckypops]

Reverse rotation water pump? Damn man I dunno, hope it's something simple.

I am using the OEM serpentine setup with the vortec water pump.

i'd have to say the same thing, sounds a little to suspicious to be a stuck thermostat, where did the motor come from, how many miles, etc...

Motor came from a suburban that I bought for parts about a year ago, Dont know the mileage, the motor ran good when I got it, but it had sat in the barn for a year after i pulled it before i put it in the truck. It did get some water in the cylinder walls and froze the motor up but I got it freed up ok.

Sure makes me think I missed the problem in the first place, I was never able to drive the burb cause the trans was fried. When it sat in the barn it some how got water in the cylinder walls but I still dont think it was rain water I am thinking now that the heads leaked the water in the cylinder walls.

 

[Joshua8336]

so check em. and if they are bad, step up to some aluminum ones!

 

[oneluckypops]

so check em. and if they are bad, step up to some aluminum ones!

Bills, wife, 2 kids, all goes again stepping up 2 aluminuim heads lol. would be nice though.

 

[Joshua8336]

point taken. good luck!

 

[HotRodPC]

I wouldn't go jumping to worse case scenario right a way. Obviously water isn't circulating or getting past the Tstat if the upper hose is cold, but the water in the block is overheated water. Is that what you're saying? Does sound like a Tstat to me. Something is blocking the coolant for circulating. How about the radiator? Is there a clog in the lower portion of the radiator? And if it is a serious problem, maybe just head gasket, not heads.

 

[oneluckypops]

I wouldn't go jumping to worse case scenario right a way. Obviously water isn't circulating or getting past the Tstat if the upper hose is cold, but the water in the block is overheated water. Is that what you're saying? Does sound like a Tstat to me. Something is blocking the coolant for circulating. How about the radiator? Is there a clog in the lower portion of the radiator? And if it is a serious problem, maybe just head gasket, not heads.

coolant is getting past the thermostat, the upper hose isn't warm because it isnt running long enough to warm up, the gauge is spiking because the coolant is being forced away from the sensor from the compression leakin into the coolant, which is also why the top radiator hose is tight, With the cap off coolant is just pushing out the top of the radiator.

 

[HotRodPC]

Ahhh OK, so your thinking a head is cracked and compression is leaking into the coolant chamber. Still might just be a head gasket. You can always hope.

 

[Manbearpig]

Try a new rad cap?

 

[oneluckypops]

Ahhh OK, so your thinking a head is cracked and compression is leaking into the coolant chamber. Still might just be a head gasket. You can always hope.

Yea I HOPE but honestly given the reputation on SBC heads I would be suprised.

Try a new rad cap?

although that is a likely culprit, its blowing the coolant out pretty quick even when the cap is off,. But that was my first thought.

 

[johnmc]

"T" stat could be in up side down? did you look? pull it out and start it up ?i would start there.

 

[crazy4offroad]

Start it with the radiator cap off and see if compression is bubbling the coolant. I would also remove the t-stat for diagnostic purposes.

 

[oneluckypops]

UPDATE

Ran a compression test, It wasnt really a trully fair compression test as I couldnt crank for each cylinder till MAX pressure was recorded. I cranked the motor for 8 seconds on EACH cylinder. The plugs show NO signs of antifreeze burning, there is also NO coolant in the crankcase.

#1 150
#2 140
#3 135
#4 130
#5 140
#6 140
#7 140

The Percentage of difference between the lowest to the Highest reading is IMO NOT enough to suspect and kind of compression leak, However the only way to PROPERLY diagnose it any further would have been to use a cylinder leak down tester. Unfortiontly I do not have 1 at my disposal.

I did pop the thermostat out, amazingly there was coolant that had ran out of the upper hose when removed, But the Intake didnt have ANY coolant in the motor. I figured what the hell I had an extra thermostat in my truck already. So I filled the engine block full of coolant thru the thermostat opening, then installed the new thermostat, filled the Radiator back up and started and let it run with out the cap on it. Now it did just fine, thermostat opened never built any pressure in the upper hose.
So I put the cap on LOOSE and same thing everything was fine, Just for ***** and giggles I went ahead and tightened the cap down. SO FAR EVERYTHING IS WORKING OK.

Fellers I feel like I am a confident technition, HOWEVER I have never liked diagnosing coolant related issues, if I had a leak down tester I would be alittle more at ease with diagnosing them. But in your opinion what exactly happened? Theres only 2 things I can see that may have happened and 1 of them I have never seen before in a SBC.
#1 Thermostat was stuck closed? I could open the thermostat by hand but could defintly feel a click to it when it first opened.

#2 Air locked, I have never seen this in a SBC, However I do have the heater hose looped from the intake to the pump, and the loop sticks up above the motor, could have I had an air pocket there that caused my scare?