351C Running Hot

Chifo Jr · #1 (**permalink**) 06-07-2003, 05:59 PM

My just completed 351C seems to be running pretty hot ie: 220 and puking when at idle. The thermostat is 180 degree and I have a fan that comes on at 190 degree. Any ideas where I can start to get this thing sorted out? Air locks etc?

kountzecobra · #2 (**permalink**) 06-07-2003, 06:42 PM

Are you still breaking-in the engine? If you are try a large shop fan in front of the radiator. Does it go over 220 degrees? Have you driven the car yet? Fan may not be flowing enough air through radiator. If it cools down while moving, then you need more fan. If it doesn't, either you have an engine problem or the radiator isn't big enough. Make sure the thermostat is opening, also, below the thermostat and inside the block, there is a pressed-in washer that slows down? the water flow. Some have left it out and they will run hot without it. Lots of variables here. Make sure cap is good and all air is out of the system too.

Daniel Jones · #3 (**permalink**) 06-07-2003, 08:00 PM

> My just completed 351C seems to be running pretty hot ie: 220 and puking
> when at idle. The thermostat is 180 degree and I have a fan that comes on
> at 190 degree. Any ideas where I can start to get this thing sorted out?
> Air locks etc?

Are you absolutely sure you have a 351C thermostat and that the block
still has the brass ring in it? The Cleveland uses a special thermostat.
They have a shoulder which is sized to match the brass restrictor ring in
the block (make sure it's there) which other thermostats do not have.
Using a Windsor thermostat (which the parts counter monkeys will give you
half the time) will lead to over-heating because coolant will bypass the
radiator. The same thing happens if you remove the thermostat. I recommend
the Robert Shaw 351C thermostat. It's quick acting and has bleed provisions
(ball bearing check valve).

Puking at idle after a rebuild can also come from using the wrong head
gaskets or putting them on backwards. There should be a tab sticking
out from between the block and heads on both sides that says "front".

Check to make sure the lower radiator hose isn't collapsing (there should
be a spiral winding inside the lower hose to keep it from collapsing).

Dan Jones

Chifo Jr · #4 (**permalink**) 06-07-2003, 09:29 PM

Thanks for the replies... I've noticed you are the Cleveland experts here so I appreciate your input. I'll add some more information: When I did the initial start I utilized a shop fan and was able to run at 2000 rpm the first 20-30 minutes with the temp staying below 200. While I did the engine build some 12 years ago I really wouldnt think that I would have placed the head gaskets on wrong. I am pretty meticulous with details. I will remove the T-stat housing to verify that the brass ring is in there but I do recall seeing it there before. As far as the t-stat is concerned, one of my shop guys picked it up at Pep Boys and more likely than not just got one off the rack. This could well be part of the problem. There is no spiral internal to the radiator hose but most of it is stainless tubing with just two short sleeves to transition to the block and radiator so I would be surprised to see collapsing over such a short area. Any other thoughts are appreciated.

PS: I have tried to be sure that the air is completely purged but am having some difficulty determining this. Also what is the proper rotation of the water pump? CW or CCW?

Rick Yeager · #5 (**permalink**) 06-07-2003, 11:46 PM

Chilo, our elderly dad rebuilt my 351C. It was the last engine he did before he passed away. When I started it, I had problems with overheating too. I changed the electric fan, went to a larger aluminum radiator, replumbed the water lines so that air would not be standing in the heads and water would be flowing more freely, checked for that all important brass ring which was right were it should have been, put on a fancy-dancy high volume water pump and changed thermostats--maybe a couple of times. Nothing worked. Finally I pulled the heads and found a head gasket on backwards. It is not hard to do on the Clevelands. I am not suggesting that this is your problem but I can sure tell you from being on the wrong side of an expensive learning curve that it can happen. Ha!! Hope you solve the problem with an quick and easy and cheap fix.

Rick

Roscoe · #6 (**permalink**) 06-08-2003, 04:16 AM

I've got a Milodon hi volume alum water pump for a 351C. I has only about 8k miles on it. If you are interested let me know.

Roscoe

B L & sons · #7 (**permalink**) 06-08-2003, 10:25 AM

Roscoe
If Chifo is not interested in the pump let me know what you need for it I maybe.
Bill

Chifo Jr · #8 (**permalink**) 06-08-2003, 10:53 AM

Roscoe: Follow up with Bill, I have that unit on the motor.

Daniel Jones · #9 (**permalink**) 06-08-2003, 08:46 PM

> When I did the initial start I utilized a shop fan and was able to run
> at 2000 rpm the first 20-30 minutes with the temp staying below 200.

That is interesting. Are your electric fans rotating the proper direction?
A number of Panteras were delivered with one of the fans hooked up wrong
which led to overheating.

> As far as the t-stat is concerned, one of my shop guys picked it up at
> Pep Boys and more likely than not just got one off the rack. This could
> well be part of the problem.

I hope it is something so simple.

> Also what is the proper rotation of the water pump? CW or CCW?

Ugh, I forget which is which but it is standard, not reverse rotation
like the serpentine belt 5.0L Fords.

> Finally I pulled the heads and found a head gasket on backwards. It is
> not hard to do on the Clevelands.

I did that myself on my first engine build. Shot a nice little shower
of coolant out of the radiator with the cap off.

Dan Jones

trularin · #10 (**permalink**) 06-09-2003, 06:40 AM

When building a Cleveland, there are a number of small changes that should be done to the block and head gaskets.

Block mods are done for oiling, Head gaskets are drilled to fix a water passage problem for engines that over heat. As I recall, the drivers side front water passage is blocked on almost all gaskets. You may need to remove the gasket, locate the water jacket and drill it with a 1/4" sharp drill. If the drill is dull, it will shred the material.

Sorry, I am doing this from memory, I do not have my build book with me. It could ba a 3/16" hole. You will need to check around for this mod. I think I got this from Bud Moore.

Hope this helps.

Trularin

jayem · #11 (**permalink**) 06-09-2003, 08:39 AM

Try "water wetter" with no anti-freeze. This will drop your temp 10 degrees. Jay.

peterd · #12 (**permalink**) 06-13-2003, 11:02 PM

I have just finished a 408/351 stroker, I was concerned about over heating from the get-go. Prior to the upgrade I had a 351W and could just about keep it from overheating in traffic by keeping the RPM's up. I assumed therefore that at idle the water pump was not pumping enough at low RPM, I changed to an electric water pump. The new motor makes 500HP+ and is overheating, (I have only got 20 min on the motor). I bought a shop fan from Home Depot ($99) and with the Fan infront of the car the I could hold the temp at 190. My conclusion was to upgrade the electric fans, I just finished installing dual fans (Jegs) and tomorrow I will try and see if it overheats, I will let you know. I will also note that when running at speed 80+ mph the temp would drop to 170, from which I concluded the radiator was big enough. I am not going to take the car on the road until I feel confident about the overheating at idle. I have a FAST ECU and need to tweek the parameters before I take it on the road and I want to feel comfortable I can do that with the need for the shop fan.

BTW I am running the electric water pump all the time and do not use a thermostat, I also have an oil cooler an big 9 quart Canton Pan.

Tony Radford · #13 (**permalink**) 06-14-2003, 06:22 AM

Pete, I had overheating problems with my Windsor when I first purchased the car. It came with the twin pushers. At Bill Parham's suggestion, I added a 12" puller and electric thermostat. Problem solved. Chill found a 16" puller fan that has such a low profile, it actually fits. I ordered mine this week for around $90 with shipping. If you're interested, I'll send you the company website (it's at work).

Chifo Jr · #14 (**permalink**) 07-01-2003, 12:09 PM

Well so far I have determined that the counter monkeys did provide the wrong thermostat. I am hopeful that this is the problem. I will tackle the rest of the system this week. I do plan to use water with a "wetter" additive in hopes that it will help further. Has anyone tried drilling a couple of small holes to help purge the air our of the system? When I removed the old thermostat the level sucked down immediately which leads me to believe that there was also air in the system. Any advice for purging is appreciated. We will see

bittentoo · #15 (**permalink**) 07-01-2003, 01:20 PM

Chifo,

I hope that the easy fix will cure your cleveland problems but I have my doubts. As been mentioned several times in this thread, I too believe that you have one of the head gaskets on backwards. How do I know? Because I too have made the same mistake. It is VERY easy to put one on backwards on a cleveland even though you are being very careful. I almost put the head gasket on backwards on the last cleveland that I built and I knew what to look out for!

If the motor was just running hot, woukld think that you had a cooling problem, but puking the water out tells me that there are other problems.

Good luck

Chifo Jr · #16 (**permalink**) 07-01-2003, 01:43 PM

One thing I have been told is that the practice of plumbing a "T" style filler fitting in the top radiator hose is not a good idea as it is on the pressure side and coupled with a high volume pump could lead to overcoming the 7 psi pressure fill cap. I sure hope it is not the head gaskets. I built the motor about 10 years ago so I really cant count on memory but I am going to feel like a real dick if its the head gasket

niles · #17 (**permalink**) 07-01-2003, 02:35 PM

Chifo:

I just went thru same thing with my 393 clev.
I had good water temp reading(80C) but would puck when I stopped, also boiled(sound like tea pot) inside of front of engine.

I found a bad(new) tee radiator cap!. I found the problem after a week of work with the eng builder by blowing into the punk tank overflow tube. I found that I could blow air back into the cooling system. Cap looked perfect, just was'nt sealing and acting as a pressure relief valve. What was happening was with no pressure; at idle or after shut down the water was exceeding the boiling point and flashing a big bubble in the hot head area and the expanding bubble would force water out the overflow

New cap and a good purging of air(very important) no more overflow

gn

Clois Harlan · #18 (**permalink**) 07-01-2003, 02:43 PM

Here is an easy way to bleed the air out of your system. At the temperature sensor that is located just behind your thermosat, loosen the brass fittings. Start your engine and as your coolant circulates it will force the air out of the engine at the top of your manifold (sending unit sensor). Once the water starts to flow out of your sensor tighten it back up and then turn your engine off. You may need to do this once or twice to purge all the air out of your system. Do this with a cold engine. Just like bleeding your brakes.

Chifo Jr · #19 (**permalink**) 07-21-2003, 09:02 AM

Well I have now exhausted all of my options to correct my overheating problem the easy way. It seems like the heads come off next to verify that the head gaskets are the problem. I did find that the thermostat was incorrect and replaced it but it did not solve my problem. One thing that is baffling is that the temp does stay pretty stable for a few miles then all of a sudden just jumps way the hell up. I did think of running a set of twin fans in addition to the 16" rear draw thru fan already in place but I dont want to place a bandaid on a bigger problem.

Can anyone give me some advice for the best head / intake gaskets to use for this job?

Thanks to all that have responded and I will let you know how things turn out.

rdorman · #20 (**permalink**) 07-21-2003, 02:47 PM

...... you do have the restrictor in the block below the thermostat don't you?
Rick