I need help! I've got a problem with the engine not cooling.
Now I know this is NOT a stock motor, but I really need some tech help here to find this problem so I can enjoy my labor's fruit.
This same motor ran OK for 4,600 miles on the Power Tour in '04. The only changes to it were the changing from 3x2's to 2x4's and a bigger Comp cam. It's a 454 out to 468, Brodix alum heads and B&M 671 Mega blower currently overdriven slightly. It's got a CSI 35gpm elect water pump up front (appeas to be flowing water properly) and 'had' an aux in line elct pump in the rear.(which di show signs of leaking and was bypassed with a tube). Cooling system hods over 6 gals of liquid. 2 'Be Cool' alum rads with 10'' Spal puller fans in shrouds, and 1-1/2 qt expansion tank. Air is picked up from two 10" dia tubes behind the axles under the body, exiting out the top rear deck. Fans run on thermastats set @ 165* (working properly). I've run no restrictors, Moroso's restictors large and small, and a 160 thermastat, all with no change in effect. I've run 50/50 anti freeze and Royal Purple Ice.
A leak down pressure test on the cooling system held @ 22 lbs for over 1/2 hr without any drops. A cyl compression test showed only 1%-2% on all but #4 & #8 cyl, which dropped over 50%, and we could feel air exscaping out the valve cover's breather on those two cyl, so we pulled the pass head. Upon pulling the head, we saw no signs of any problem around the valves or chamber surface. We filled the combustion chambers with liquid overnight, no leakage showed from those cyl's. Sent head to machine shop for other test, not back yet. No sign of any damage indicating problems with rings on bores. No marks on pistons or on head gasket indicating any kind of seepage/leak. Before I go any further and drop the oil pan and pull the two pistons in question to inspect the rings, I was hoping you all might have some other suggestions! I've read up on the Stewart aux water pump which flows 55 gpm and I'm considering it to increased flow. Not sure if that's the problem, and @ $400+ for the pump, I'm thinking twice, if that won't cure the problem.
At highway speed (steady 2,200rpm's) the temps climb and never level off. Water begins to be pushed out at 190* causing low water levels and overheating. Cyl head temps climb (L-R equally) to about 260*. Exhaust gas temp shows 975* to 1100* for the each cylinder while driving at highway speeds. Oil temp stays at 100*-120* (oil cooler in use). Timing is at 38* total, and retarding it a degree or two made no difference in keeping it cooler. Granted, I live in Florida and outside temps are in the mid to high 90's, but it use to run OK in this temp. Any tech heads out here? HELP, please!

 

Two things....The coolant beign pushed out of the radiator cap at 190* has to be fixed. Possible causes are cracked head, block, head gasket failure or weak radiator cap. The second problem is the leak-down. Possible causes are rings, valves, cracked cylinder bore or head gasket. Only common denominator I see is the block. Inspect closely!

 

Replaced the 'Be Cool' supplied cap (14lb) with a 18lb cap but no change. Visual inspection didn't reveal any signs of cracks in the head (why it's sent to machine shop for magnaflux and other tests) and no visible signs on the cyl walls. Know if we can't find anything this way it will require pulling the motor and doing magnaflux checks. Th motor runs VERY strong and has No misses. It was running rich and we had been playing with jets and tail pipe sensors to fix that prior to pulling the head once we found the cylinder problem. It still could be a gasket problem since the intake gaskets were destroyed pulling the intake, but no signs of leakes on the mating surfaces and the head gasket looks fine. Block is "O" ringed with ss wire. Thanks for the suggestions though. Glenn

 

Leak down shows leaks at cyls, overheating issues and high coolant pressure. In a reply to one of your emails I asked if you had done a coolant test for CO2, have you done that and also to measure coolant pressure. From what i'm reading it really sounds like a crack in the block or head or a head gasket issue. Normally @ 190 the coolant pressure is nowhere near high enough to open your 18psi cap.


Looking at the pic #2 & 8 is looks like the pistons are a lot cleaner, no sooth like the other 2 indicating a washing by leaking coolant. It may just be a small leak, a haritline crack that expands when the engine heats up, enough to leak a little into the cyls and enough to pressurize the coolant system to open your cap.

I don't think a water pump will do you any good, neat thing..you have a cyl. temp gauge and if it was too little flow you would see the cyl temps fluctuate and be very high. Do you have a gauge for each bank? If it was a flow problem you would see an alternating temp rise and drop from L to R as each bank gains temp & pressure and fights over dominance to expell coolant through the thermostat.

Can you snap a closer pic of the cyls & pistons??

 

Just wondered if you ever did the "combustion gas in the cooalant test" ? And if so, the result.

Your cooling system sounds interesting.
Can you post some pics of the radiators setup and the 10" cooling ducts?

If you don't have combustion leakage the next most common cause of overheating at speed would be the radiators not getting enough cool air and overextended. Most of your sysmptoms are also classic to that. What size are your rads? It sounds like you could be getting hotter engine and exhaust air into your pickup under the car. It sounds like a novel setup, but I have never heard of it before. Most rear cooled radiators have side scoops.
Here is an interesting read for cooling non stock.
http://www.streetrodstuff.com/Articl...g_Suggestions/
Also I have read tests that show synthetic oil can reduce engine internal temps by as much as 30*

At this point, your toughest part is finding a definitive answer, so hopefully your macine shop will find something, good or bad.

I'm in South Florida so I'm very familiar with cooling.
Love to see those pics.

 

Considering all the plumbing involved could it possibly be "air bound" ?Just a suggestion,,,Peace,,,Moosie

 

50% leak down with air coming out the valve cover points to rings. Pull piston 4 & 8. With a blower I would entertain the possibility of broken ring lands.

 

3 suggestions, as I've had cooling problems too living down here in FL.

1. Triple check for vac leaks. If it WAS running OK, then changed all of a sudden, maybe a cap or vac hose fell off somewhere.

2. This I learned from Matt Guber (dyno tuner New Smyrna) Retarding timing will make it run hotter. You might need more timing at cruise. Normal motors will run 52 degrees at cruise with a vac canister.

3. Any chance the cooling system is being pressurized by leaking cylinder compression?

 

Ya gotta get all of the air out as well. do you have a bleeder at the highest point in the system?

And from the description any of the local highpoints that can trap air?

Coolant pressure guage?