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19 replies

serious overheating issue

H horacecopeMember
Need some help in determining the cause of a serious overheating on my 74 Pantera.

In summary:


Block hot dipped and cleaned prior to machining + 30. Lifter bores sleeved. New forged pistons and rings fitted. New Trickflow fully assembled cylinder heads fitted with recommended Felpro 1013 head gaskets. ARP Head Studs. New Robertshaw thermostat from Marlin with brass plate fitted. New cast iron std water pump. New radiator core. Twin electric puller fans.

Problem: Engine is spewing out the coolant within a minute or two of starting. Engine getting boiling hot while radiator is staying cold. With and without pressure cap.

Several checks for air locks by raising first the rear then the front and venting radiator.

Retorqued heads

Heater inlet and outlet pipes removed at engine. Engine started and no water coming out of either pipe. Thermostat removed and still no water coming out heater pipes.

Heads removed and head gaskets are fitted correctly with front at front.

Water pump brand new and impeller intact. Stock pulley

Thermostat removed. Water put into engine with water pump removed and water flowing out of water outlets at front of the engine. Each of these holes blocked off at different times to check water is flowing through block

Cylinder head gasket and block compression leak test done using test dye. No gas leaks.

No water in oil and no visible cracks in cylinders.

Car not yet been on the road due to these issues.

Been onto Summit as the casting on the heads states SBF 5X and OA2 1207. Never considered the 351C a small block so hopefully the heads are correct. Part No ordered correctly as per 351C TFS 51616204 but not stamped anywhere on heads so can't be sure.

I notice the coolant holes in the Felpro 1013 head gasket are smaller than stock Felpro 351C head gasket, would that make a difference.

Serious water circulation issue I feel but don't know why. Anyone got any clues.

Cheers
Original Post

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C cenglesMember
Dear Horace,

On a couple of my engine rebuilds, the engine process took so long that the radiators dried out and the schmutz inside clogged them. Upon engine installation, they ran hotter than before. After I decided that it was not due to excessive BTUs from my glorious engine rebuild, I had the radiator cleaned and flushed by the radiator shop. Both times this solved the problem.

However....mine did not act as dramatically as your's is acting. FWIW.

Warmest regards, Chuck Engles
garth66garth66"When speed is the only thing that counts"
quote:
Brass restrictor plate is fitted and the overheating is happening with and without thermostat fitted.

Note that the 351C WILL overheat WITHOUT a thermostat.

Symptoms sound like head gaskets were installed backwards, but you ruled that one out. Are you using stock pulleys and belts (and not some serpentine setup)?
lf-tp2511lf-tp2511Member
Damn complete trouble shooting. Smiler

I would look closer to the water pump, as surely some coolant should have come out the heater tubing outlets.

Could the impeller be incorrect for the rotation of the shaft?

Are you absolutely sure the impeller is firmly connected to the shaft, even under a heavy stress load?

BTW, from what location is your coolant loss occurring?

Larry
H horacecopeMember
Hi Larry

Straight out the top of the filler bottle with and without pressure cap.

The system is definitely pressurising from somewhere but have eliminated compression leaks using the sniff tester. No visual evidence on the gaskets of gas leaks either now that heads are off.

Need somehow to get the water pump tested or borrow one I know is working. Water pump was bought new and has stock pulley, V belt

I am waiting to hear back from Summit Tech as I am leaning to it being wrong heads or wrong gaskets. However the gaskets line up well when put up against old stock heads ????
B bdudMember
quote:
Originally posted by C. Engles:

On a couple of my engine rebuilds, the engine process took so long that the radiators dried out and the schmutz inside clogged them.

Horace says he has a new radiator core so hopefully not that.
No water coming out of the heater pipes is not right. Any water in the block / water pump should cause water to come out of heater pipe when the engine is started. The smaller pipe / fitting on the pump is the return, you might have a vacuum - temp sensor in the port or blank plug next to it. The port coming off vertically of the block is the supply to the heater.
I presume when you took these hoses off water did come out as you had bleed the radiator?

When bleeding the radiator, I generally do this with the rear of the car raised, heater control to hot and bleed as much as possible from the radiator top bleed valve. Start the car with the rear still raised and keep adding water. When the radiator opens, close the cap. You should generally be able to drive the car at that point. Allow car to fully cool and check water level, check radiator bleed valve also for air. Also check expansion tank is ~ half full.
It sounds like your water pump is not getting a water supply.
If you connect a water hose to the water pump inlet does water come out of disconnected heater hose connections?
You could try with a water hose connected to the heater connections, do you get water flow?
George PGeorge PAdmin.
The only thing that can prevent coolant circulation is the wrong head gaskets, improperly installed head gaskets, a "loose" coolant pump impeller, or a serious amount of air that hasn't been bled-out. Mis-orienting one or both head gaskets is a common 351C assembly error. The tell-tale evidence that the problem is a head gasket problem is the sound the engine makes when it heats-up, I call it "gurgle and surge".

The head gaskets should have the passages/holes as indicated in the picture below, those passages/holes should align with passages/holes in the block, the cylinder heads should also have "matching" passages/holes in the same locations.

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goodrocgoodrocMember
Horace, what about the Gaskets/Timing Cover? The Pump sends Coolant via the Holes in the Block/Timing Cover, then vertically up primarily via the large Hole at the rear of the Block as George marked. It also flows via several smaller Holes between the Bores which are (intentionally) limited by smaller Holes in the Head Gasket and then Exits the Head and flows back down into the Block at the front and then flows to the Thermostat and reurns to Radiator. Its definately blocked somewhere either between the Block and Heads or Block and Waterpump.
H horacecopeMember
I am not too sure how to post multiple pictures in one post so apologies for the number of seperate photos.

Pics attached of the heads, gaskets, block, front of block, water pump etc. Anybody see anything from these pics that might not be right.

No part numbers on the water pump but purchased from a reputable US spares shop over here.

As part of the process, a water hose was put in the lower pipe from the filler bottle, water ran through the radiator and out the other side to the water pump inlet so does not seem to be blockages there.

Heater hoses were removed and filler bottle filled up, water ran out the heater outlets in pump and block. However it didn't run out when engine started why???.

As I mentioned earlier it would be good to try with a water pump that we know works. Thats the next thing to try. The impeller on the back of this pump is solid and secure. Can anyone tell from looking at it if its on the wrong way round.

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  • SDC11088
goodrocgoodrocMember
Horace if you have an "open" system with Hoses connected here and there to try and spot if water is flowing it will not! When system is closed (all hoses connected and Cap on) and Engine is started and run it will warm up at idle and possibly there will be air trapped in the Heads! It will NOT flow and it will NOT cool as long as air is trapped. You need to assure that the air can migrate out via the Thermostat Cover and in to the fill Bottle when the Thermostat opens. Its best done (in my experience by raising the front of the Car as much as possible) and observing what is the highest point of the system, Air will go there as Air MUST go up it will only be able to descent momentarilly if you rev the Engine. The Air in the Radiator can be evacuated with the Engine off. I dont know if you followed this procedure but for sure if system is not closed up it will suck in bits of Air and only add to the problem.

When I look at the Photos you attached all looks normal. I am not 100% sure about the Pump actually there are reverse rotation Pumps available and I dont have one here I can compare the Impeller with unfortunately.
R rickMember
I spent a stupid amount of money solving this one recently. In my case a lower hose was collapsing completely flat because my water pump worked so well it pulled all the way around a closed loop to the pressure side of the pump. The weakest link failed. Make sure you don't have any long (more than 6 inches of green stripe) hoses in the system.

We looked everywhere but down... :-/
B bdudMember
Horace, your water pump looks like the correct style. It has the bypass port so you will need to use the brass plate and 351c style thermostat which you say you have. Do you have pictures of the brass plate installed?
I am not sure a reverse flow water pump was produced for a 351c.
Have you tested the thermostat with boiling water and a thermometer?
George will be able to comment better on the heads and gaskets but they seem correct. Do you have a picture of the right hand block with head gasket on? The "front" on the gasket may well be facing downward but the large round port needs to at the front on both sides.
Good to hear that hose pipe test showed you had no blockage in the block etc.
For the water pump to be primed and push water it will to have water past the impeller. You will have to raise one end of the car and ensure all air is vented fully.
You should use an additive or anti-freeze to stop the rust in the block.

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