Hey guys
I have a 1978 F250 that has a new 400 (my old engine threw a rod at 67k miles). This rebuilt engine runs HOT!!!! I have a new 4 core (I think, it is the biggest radiator avail) and its still running hot. I have replaced the t-stat and all of the cooling hoses. I was told that a rebuilt 400 runs hot because the cylindar walls are so thin. Is there anything else I can do?

Another question, is there a coolant overflow tank available for these years? I can't seem to find one.

 

Was it bored over? If it was bored out too much, it'll overheat no matter what you do.

The M engines should never be bored over .30.

 

I am not sure, i bought the 400 long block (with heads) from a machine/rebuild shop. They do this for a business do I hope that they didn't bore it over too much. Would installing an electric fan along with the engine fan help??

 

Hope they didn't install the head gaskets backwards.

Dre'
1978 F-150, 460ci(750cfm,Edelbrock Performer,Dynomax Ceramic Coated headers,etc.)Auto-C6,373:1 - 9" Posi.

 

[updated:LAST EDITED ON 03-Aug-02 AT 03:37 AM (EST)]Hey Dre',

I'm afraid the reversed head gaskets may be my last obstacle to face.

I have a 1973 F-250 3/4-Ton Explorer Trailer Package, 390 V-8 with 200K(+) miles on her. (I've put the last 100K on her in the last 5 years.) I had a compression check done last fall & only 2 cylinders are running a bit less than 100%. 'Ole Blu will still do 120 "uphill". I baby it quite well. It's still a great powerhouse, but running hotter than H*ll!

My former father-in-law ordered it new outta the factory & when he died, Mom gave it to me to use as a work truck. (I own a small construction restoration biz.)

I just moved to Sacramento and it's running HOT in all types of traffic within 10 minutes. It overheats regularly if I drive any distance over a few miles. I carry a good book & lots of water!

It has a 4 yo 3-Core radiator, I just changed the thermostat to 160, new radiator cap, flushed the system 2x's, Water Wetter additive, changed to a flex fan, etc. All the obvious possibilities, praying it's "not" the head gaskets!

I had a former friend machine the heads last year (since I had to replace the exhaust manifolds & donut gaskets) & have had nothing but trouble since. (This guy is a Jeep Jamboree mechanic here in the Sierra's!!! Shoulda never let him touch a Ford!)

Any last thoughts before I grab the crying towel & have the heads torn off for the 2nd time?

JB13, aka Jane

 

Make sure your timing is correct and the vacuum and mechanical advance mechanisms are working correctly.

 

>Hey guys
>
>...
>
>Another question, is there a coolant overflow tank available
>for these years? I can't seem to find one.

From my research and talking to a Ford mechanic, Ford didn't offer a coolant overflow tank. I was looking for one for my truck also. NAPA sells a generic one, but it is pretty small and shaped to fit the curve of an inner fender wall. It didn't look like it would fit the truck very good so I'm still looking.

 

You can make your own catch tank out of some hose and an antifreeZe jug.
On the 400 engines, its possible to connect the Distributor Vacuam advance to the wrong port in the Carb. That will cause it to run hot.
I just cant remember which is which, but one Port is reduced, and that's the one for the Vac Advance.

 

[updated:LAST EDITED ON 04-Aug-02 AT 01:49 AM (EST)] Sounds like head gaskets to me. I would run a pressure test on the cooling system. If there is a leak, then find out if it is into one of the cylinders. I would also, remove the sparkplugs and fill each cylinder with compressed air, see if any of the pressure bleeds of into the radiator.

You said that it does this in traffic, Do you still have the fan shroud on it? If you have one, is the fan clutch in good shape?

How good is the water moving thru the radiator at low rpm? You could have a worn out waterpump.

The radiator could need to be dipped and cleaned.




P.S. Auto-Zone has a decient add on overflow bottle. It is square and will fit next to the radiator. All you have to do is run 1 self tapping screw thru the core support. The 73-79 trucks didn't come with any kind of overslow bottle. They came out in 80 when they changed to a cross-flow radiator.

 

>Make sure your timing is correct and the vacuum and
>mechanical advance mechanisms are working correctly.
>
>
>-Eric, Torque1st,
>[link:www.ford-trucks.com/guidelines.html|FTE Moderator]
>Fix it right the first time! It's easier than doing it over!
>
>Then- Drive 'em forever!
> [link: motorhaven.autoanything.com|How YOU can support this site!]
I will check into that. Luckly when my dad bought the truck he also got all of the shop manual's with it. So I should have the diagram for the vac lines.

Any other suggestions? I didn't install the engine (because the warrenty was only valid if it was installed by an ASE mechanic). Is there anything else that could be hooked up wrong (or not at all) that would cause it to overheat?

I need my truck running right by the 17th. I don't really want to pull a 25ft boat with my SUV!!!

 

I once read about a similar problem in one of the off road rags. They had a 350 in a jeep with a 4 core radiator. They changed eveything and finally realized that the 4 core radiator restricted the air so much that the water was not cooling. They went to a 3 core and the temp dropped. Wierd. Sounds like the fan just couldn't suck enough air.

I also saw a problem solved by restricting the flow so it stayed in the radiator longer so it could cool. If the coolant blasts through the radiator too fast it does not get the opportunity to cool.

You say you went to a flex fan. Did you retain the fan clutch? These things are notorious for this kind of problem. The clutch should be hard to turn. Ford clutches work much better than GM. The fan should sound like a tornado when hot. It's sometimes not obvious when one is weak.

Something to try: Drain the coolant and replace with water. Keep the radiator cap off and remove the top radiator hose coming from the engine. Keep the radiator full with a garden hose. Let the hot water from the engine pour onto the ground. Get the temp up. This ensures cool water to the engine. If it still overheats you either have the wrong or reversed head gaskets or some other obstruction.

Have you checked your water pump? It may be fragged. The fins degrade over time and it may not be moving enough water.

ledgeclimber

 

hey guys i had this same problem with my '71 429, i just posted on here about a week ago, and did all the same stuff flushing radiators, looking for electric fans and so on, but then i finally decided to chekc the new termostat i put in. wound up that after i pulled it out and ran it with out one it cools fine (actually a little too cool). i need to put one in before it gets cold here but i just figured its worth a shot before ripping your heads down!!
just my two cents,
nick.

 

If the problem goes away with no thermostat then either the thermostat is broken or you are using the wrong one. There are two basic types. The butterfly type and the cup on the bottom type. The latter is a high flow rate version. Robert Shaw brand makes both.

I also had a butterfly type break apart and the buterfly lodge in the opening and restrict it.

Ledgeclimber

 

>If the problem goes away with no thermostat then either the
>thermostat is broken or you are using the wrong one. There
>are two basic types. The butterfly type and the cup on the
>bottom type. The latter is a high flow rate version.
>Robert Shaw brand makes both.
>
>I also had a butterfly type break apart and the buterfly
>lodge in the opening and restrict it.
>
>Ledgeclimber

Ok I will give that a try..
Thanks