I just installed a rebuilt 302, but I'm having water temp problems. It seems like the faster you drive with it, the hotter it gets. While driving 65, for about 20 mins the temp gauge will reach about 230. Here are some specifics about this engine:

The block is a D40E which makes it a 1974 block.
It is bored 40 over
It has 1969 351 Heads on it.
Has a street cam installed.
It uses an 4bbl intake manifold off of a 289, K-code Hi-Po.
I am using a 50-50 mix of Prestone (All makes and models).
This engine mounts in a 56 F-100. It uses a single core radiator, and no fan shroud, with a flex fan. The fan is about 2" from the radiator, and is "pulling" air into the radiator
The themostat is a 160 and opens at about 168 (verified by dropping it in a pan of water heated on the stove. The temp gauge is electric, and shows 170 when the thermostat opens. So it looks like the temp gauge is accurate.
The radiator has been boiled out and flow tested and all looked good.
I have tried both 7 PSI and 18 PSI radiator caps on it.

There are so many points here to ponder. Any advice is appreciated!

 

13psi cap, change to a 180-195* tstat, install a shroud.

btw what year / model vehicle did the water pump come off of, At some point they changed rotation directions on the pump. If your pump is running backwards all its doing is cavitating and not pushing coolant correctly.

Also with a flex fan, the faster it turns the less is does as the blade flatten out. So i would either put a stock fixed fan or a clutch type fan on it. THere are 2 different fixed fans, a 4 blade and a 5 blade (HD cooling).

Where are you located? if in a hotter climate try less anti-freeze more water, say 60/40 mix (h2o / af)

 

Thanks! Good question about the pump! It was thepump that came on the engine. This engine was pieced together from different ones so it may of came out of a c.c.w. rotation belt assembly. Does anyone know what the ford part# should be for water pump on this engine?

 

Grey brought up an excellant point. I bought this engine used from a fellow who really didn't know the history of it. When I took the engine to be inspected by the machine shop, they mentioned the timimg cover looked like it came from a boat such as a Mercruiser. They then wondered wheter the engine was standard or reverse rotation. It turns out it was standard rotation. But what I am wondering is....just maybe someone bolted this C9JE-6059A marine style timing cover along with its' water pump on this D40E-6015A block. Maybe the timing cover came off a reverse C9JE 302!

I know.....maybe,maybe maybe. I guess I would like to try to find out if this V belt driven, standard looking water pump is actually a correct rotation one. How do I find out for sure without changing it? By the way the only numbers I see on this the pump is 5341 in the upper right hand corner, and 14061 on athe lower right hand corner of the unit.

BTW the machine shop put this engine on the test stand and ran it successfully. But they did not use this pump, they used an electric one.

 

I was doing some more troubleshooting on this. About the water pump, I believe it is standard rotation, as the lower radiator hose is cooler than the top. And with the radiator cap off,and thermostat open, I see coolant flow downward thru the radiator side tank. While I had the cap off, with the engine idleing, and coolant flowing, I took an old, trusty, mechanical water temp gauge, and dropped it's capilary tube temp sending unit into the radiator. It's reading 170, but the electric gauge inside the cab is reading 210. Hmmm. It's looking to me like my electric one could be lying to me. The reason I changed to the electrical one, is the intake manifold (C5AE series manifold) on this engine has an 1/8" NPT fitting for a temp gauge, while the old engine I took out, had an intake manifold with a 1/2" fitting on it. Thus it used the mechanical gauge. I am thinking about changing the water neck to another one I have with a 1/2" threaded plug on top of it, for a vaccum operated valve, that this engine does not use. And then using that for my new mechanical water temp sample point. I know there is one problem with that, if the thermostat does not open, then the engine could over heat without showing a high temp on the gauge. To get around that I would install one of those thermostats that stick open when it dies.

Am I on the right track here?


Grey's suggestions are good, and I should do those too. I'm just trying the cheap route first.

 

You're putting your trusty mechanical temp gauge's sensor into the cool side of the radiator, so it WILL read much lower than the sensor that's mounted in the intake. So your electric gauge may very well be indicating the correct temperature.

A higher pressure cap increases the boiling temperature of the fluid. That improves heat rejection at the radiator, if that's working properly. I would definitely put a shroud around the fan, and maybe put a spacer on the fan to put it closer to the radiator.

Just curious, are you seeing any of the obvious signs of head gasket leak? Smell of fuel in the coolant, overflow while running?

 

Cool side of radiator....that makes sense! No signs of head gasket leaks, no gas odor in the coolant, and there is no overflow while it's running. The pressure was bumped up to a 15 psi, but still has the same problem. So I guess I better start looking for a shroud...and a new fan. Hopefully get to keep the radiator.

 

Speaking of the radiator, you can check to see if it's got plugged core tubes. Run the engine until it starts to get hot. If you can't get direct access to the front of the radiator, you will have to get to its back to do this. Turn the engine off and feel the upper core area with your hands. The side near the inlet should be hot, especially in the upper areas. As you feel across to the other side, it should gradually cool down.

I had a radiator with its upper core tubes clogged up with hard water residues, and most of the upper area felt cold after the engine warmed up because very little coolant was flowing through it. The engine would overheat whenever I was trying to drive up hill. I was able to have it cleaned out by a local shop, and it stayed cool under the hottest conditions afterward.

 

Thanks XLT! I give 'er the feel test. I did change to a 13 psi cap. That seemed to make it run about 10 degrees cooler. Tomorrow I plan on changing the thermostat from a 160 to a 180 that worked well in the old engine. We'll see if that makes a difference.

 

Just a couple things to keep in mind. Newly built engines tend to run a little warm, timing advanced too far can cause higher temps, fan shroud is a must. Are you running a recovery tank? My newly built 306 for example would get too warm and push coolant out overflow till it reached the proper 1" below radiator neck. After installing recovery tank, able to fill rad to the top which added another 1/2 gal of coolant counting the recovery tank. That and the fan shroud cooled it right down. Your results may vary.

 

Well I think I finally have an answer to all of this. Long and the short of this, it looks my my electric water temp gauge is lying to me. I decided to try the simple stuff first, I put on a 13 psi cap, that seemed to lower the temp about 5 degrees. Then I installed a 180 degree thermostat, but that didn't change much, but made the engine look like it was running a little warmer. So I finally decided to buy one of those infra-red temperature guns. After a road run, with the water temp gauge reading around 230, the infra-red gun is showing about 190 on the water neck. About what you would think it should be. I also shot different parts of the intake manifold. It was also around 190 give or take 2 or 3 degrees. So I think I'll need to look for a new gauge. If you guys agree with this, do you think I could use the 1/2" threaded fitting on top of the water neck for a new mechanical gauge, instead of that 1/8" fitting on the intake manifold for an electric gauge?

 

I recommend the mechanical "Bourdon Tube" type of temperature sender. I have one on my car, and I installed it on the water neck. It's a bit odd because it doesn't start to read until the thermostat opens, but it always reads about 195 degrees with my 190 degree thermostat.

It's educational in the wintertime to see how long it takes for the thermostat to open. If it's really cold, it doesn't even open by the time I get to work.

I left the stock temp sender in the dash, so I can watch that one as well.

I think the mechanical gauge is more reliable as there are fewer parts.

 

Just out of curiosity, where did you run the Ground for the Digital water temp sender? I had the same problem with my '92, 300, and it turned out that the ground for the sender had a lot higher resistance and thus it showed and even higher temp. I ran the ground directly to a spot on the Engine block and all is Good now.

 

Tip: When putting an electrical sender into the block, don't use teflon tape.

 

Thanks for all of your replys!

Beanscoot, I agree, and I think I might do exactly as you are planning!

Timbersteel, At the back of the passenger side head, I have 3 ground connections. One to the battery negative post, one goes to the body ground, and one goes to the fram ground. I measure the resistance of the ground side of the sender to the main block ground. It is 1/2 ohm. I am wondering if it changes with engine temperature. It would be interesting to check the volatge drop between the ground of the sender and the main engine block ground point and compare it cold, then with the engine hot.

GFW,That's a good tip!! I did put thread sealer on this thing. Also while I an thinking about it. This sendor came off another engine. The main grounding point on the other engine was one of the end flange bolts on the intake manifold. I did not like that set up so foe this engine, I moved it to the more standard behind the passenger side head.