I have a '79 400M that I just stuck in my truck to replace the 400m that blew out - chocolate milk oil problem

Now this 'new' engine I got from a guy who knew a guy... it was supposed to run sweet. I did compression tests BEFORE I got it, and it was 150 or so across the board, with the first stroke jumping to 120, and the next couple 10 more a piece. SO it seemed just fine. Also has recon. water pump (no leaks, no wobble).

Anyway, after new spark plugs, wires, etc, it starts and runs great. Vacuum is at 18, steady. A throttle pop makes it drop to 5, then up to 22, and settles back down. So things seem good on the vacuum. (there is a leak in the dash that I need to find...)

I also replaced the thermostat. Put in a 160 degree one. But the funny thing is that there was no thermostat in this motor! Trouble?

The temp gauge didn't work either. New sender and it was up on the M of temp! So I purchased a mechanical water temp gauge and installed it into the other temp port on the water pump, next to the electric sensor. From cold, it would build up temp to 160 and maybe do 170, but after 2 hours of idle (was working on getting the carb set better), it went no higher.

Now, I drove it and it went as high as 215 degrees ! Is that normal? Hmmm.

One thing I did not check is the distributor advance. It seems peppy, but I guess I should break out the timing light and check tonight.

Any other suggestions????? HELP! I want my truck back already!

-scott

(Somewhat)Proud owner of a '77 F150 SuperCab & '69 Mustang.

 

215 deg should be fine. My M runs 210-212 all day, slightly higher on hot days. Mine has about 80,000 miles on a rebuild, and has run at this temp since built. Just make sure the stat is in, a good 50% mix coolant, and always use a shroud around the fan. Happy truckin'

Nathan

 

ms69, I got your e-mail, but I dont think my reply went through. Flush the system, It couldnt hurt. Check the vaccume advance to see if it holds vaccume. Make sure mech. advance is working. Also, make sure you are timing off of #1 plug wire and that the balancer hasnt slipped on the rubber damper. Good luck!

Nathan

 

Well, timing is 14 degrees. Mechanical advance is ok. Vacuum advance is working too.

I drove it today at 70 mph. Got it up to 220 degrees. I will do the SuperFlush - maybe that will loosen some rust buildup, but the water is clear with nothing in it.

Its possible this motor was bored .030, so that would make it hotter than stock. I also read that ford started running motors hotter to get by smog testing.

So I am in a quandry. Should I take it to a shop to see if they can figure out what is going on? Take the radiator to be tested / cleaned? I haven't been driving it enough to get the rad fluid level enough to see if it is using it up (sucking into combustion via weak head gasket).

Like I said, it can idle all day at 160. This is wierd.

Proud owner of a '77 F150 SuperCab & '69 Mustang.

 

Scott,

Look at the problem this way:

Your engine is able to dump the heat out just
fine as seen by the rising temp when on the
road.

Your radiator on the other hand isn't keeping up
with the extra BTUs of heat.

A few suggestions:
Back flushing your radiator inside and OUT.
Do it outside to get rid of bugs and road debri
by taking a spray nozzle and back washing the radiator by spraying from the engine compartment side to the front of the truck (I like to take the fan and shroud off first.)

You might also try using some 'water wetter'
stuff. I can't remember the exact name but CRC
also makes the stuff. It breaks down the surface
tension of the coolant so it flows better in your
radiator so it dumps more heat into the air
going through the radiator.

I run a 460/C6 in my F250 pulling trailers and
don't have a problem. I have a 4 row Modine
aluminum radiator, 195 degree high flow
thermostat and 1 can of the CRC stuff.

 

I had a 68 Cougar with an overheat problem. It ended up being fixed by taking out the 160 therm putting in a 180 and getting rid of the "performance" flex-fan. The longer the coolant stays in the radiator the cooler it gets (to an extent)the 160 opens at 160 and never shuts long enough for the coolant to cool down. I now run plastic high flow flex fans on everything. They only wiegh about 1lb and move ALOT of air (Summit Racing sells them)

 

Well, I finally think I has this one licked.
After driving it around up to 220 degrees, I let it idle in the driveway for a while, but the temp never went down. So I sprayed the radiator with the hose and it dropped immediately.

I did the Prestone superflush to clean out the block. That helped some - the water that came out at first was quite nasty.

I had the radiator rebuilt at a welding shop for $65. Guess what? the temp never goes above 195 now. Oh, I also had replaced the thermostat to a 180, but I might go back with a 160, i dunno.

Anyway, I wanted to thank people for the help. It seems to be all better now.

Proud owner of a '77 F150 SuperCab & '69 Mustang.

 

Great! I suggest leaving in the 180 stat. If its fixed, dont mess with it!

Nathan

 

 

add sea foam to your oil run a few days change oil and add prolong oil treatment next oil change that is

 

I agree with Nathan. Stick with the 180° 'stat. If it's not overheating the engine will like it a lot better and it will help with the chocolate milk oil problem by getting things warmed up enough to burn off any condensation.
Just my $.02
Greg

'77 F-250 Camper Special 400ci driver
'76 F-250 Supercab 360ci current project
'71 Mach I 429CJ in storage
'79 F-150 for parts
HONK if you like peace and quiet!

 

Ford newbe, check the date of Nathans post.

 

Good catch Brian. I guess I should read a little more carefully.
Greg