Running a 70's model f350 with a 390...


What is YOUR normal operating temp range? With what configuration (i.e. stock everything, aftermarket rad and fan, etc).


I have a long post about overheats that I am starting from scratch on because a lot has changed since that thread was started and I am looking to see what really is normal operating parameters.


What I have going on (now) is a 74 F350 with a brand spankin new 390 with brand new (not reman) water pump, new all aluminum Champion rad and a new Flexalite electric fan running wide open all the time. Installed a new 180 therm in it when I put the intake on it. I am running 205 pretty much all the time when running down the freeway and that has been confirmed with 2 separate temp senders - one in the stock intake position and one on the outbound side of the thermostat on the housing/neck. My concern is that this is too high of a temp to be normal operating condition and that once I start towing, it is going to heat up way too quick. What is actual overheat temp? 230...240...?

 

360FE, 4V, stock water pump, stock radiator, 180° thermostat, 80° outside temp.... 190° at idle according to the E-Street EFI app. A Lincoln Mark VIII fan keeps temps in check. It has never tripped the high-speed setting. Same conditions at 60 MPH and it runs 185°.

If towing, I suggest adding an engine oil cooler... a good one like a Setrab. And if auto trans, a tranny cooler.

Does your truck have a fan shroud? If not, all the fan is doing is stirring the air under the hood rather than drawing air through the radiator.

An engine should not run more than 220° IMO. Things start "cooking" plus an increase risk of vapor lock.

 

No shroud, except for the shroud that is part of the fan which is 1/8" from the rad face so it can't really pull air from anywhere but through the rad. Moves a lot of it actually. The main reason I question normal at 60 is that I am at 205 and at freeway speed, the fan is really doing nothing to contribute to the air flow. Without a shroud to speak of, it should be doing max cooling at 60mph and I would figure, like your engine, be sitting at about 185-190. 205 seems high to me. I did order a Mark VIII fan today and will install that instead of the Flexalite but 205 has me worried that the aftermarket rad is not enough. My stock rad is plugged up and is going to cost what the replacement did to have boiled and rodded out... hence the replacement.

 

In general, with a good cooling system, temp while moving down the road (cruising) should be just a bit over stat temperature. Around 185 with a 180 stat would be about right. Sounds like you are consistently running 205 so something is off.

From a dead cold start it should warm fairly fast to the stat temperature then level off for a while. Does your do this?

 

Need to do some more work and testing before I can answer that with more than an educated guess. I just put the engine in last weekend and was doing final adjustments and road testing when it crapped out the rear intake valley gasket stopping my day. Hate those cork P.O.S.'s. Going to pull the intake and reseal then start over with adjustments and temp testing. For now, am just looking to see what range I am really shooting for.


My dad says his van runs 210 all day long with 225 high end and that is his 'normal'. I am not comfortable with that.

 

Say, have you ever thoroughly flushed the engine block by removing the pipe plugs down by the pan rail? There is one on each side - basically directly below cylinders 3 and 7.

I pulled mine after draining the system and nothing came out. ...Then I poked the hole with a scribe and a torrent of grit, scale, and yuck came flying out. .. I flushed and backflushed the jackets until the water ran clear.

Your e-fan's shroud should cover most of the radiator's surface area. Some fans "shroud" is only at the perimeter of the fan blade which is not enough...

.. a Lincoln Mark VIII fan will cover about 85 percent of the fin area.

 

Yeah... the electric fan on there now only shrouds about 16.5" square. Ordered the MarkVIII fan today and will swap it with the one in there now.


As far as the plugs go, this engine is full reman. They pull every plug, rod and boil and boil again if necessary. Very reputable company so I am not worried about the condition of the coolant passages. The heat is definitely getting to the coolant. It's whether it is getting out of the coolant that is questionable.

 

You sure the thermostat is working correctly? I've gotten more than one "new" that was bad out of the box. I was also thinking about pulling the freeze plugs until I saw you said the engine was just re-done. I'd be worried about your current fan/shroud situation as well, but I see that you've got a new one coming. I'd bet that's your problem and it seems you've got your solution en route. How many rows in that Champion rad?

 

The Mark VIII fan will suck your battery dry and a stock alternator will have trouble keeping up with the electrical demand... you have or will upgrade the alternator, right?

 

I believe that the thermostat is okay but will reverify. I have senders on both sides of the thermostat and if I remember correctly, the outbound sender rises very fast to match the inbound side temp as soon as the coolant hits 180 degrees. Will double check again though this weekend.

HIO SILVER
Uh, yeah. I planned to do the 3g upgrade but the new fan will make it a priority.

 

Even WITHOUT a fan at freeway speed you should not be running 25 degrees over the thermostat setting. Either air flow through the radiator is blocked, water flow is restricted, timing is way off or the thermostat is bad.

 

Been pondering, cuz I can. When I pull the intake to reseal, I am going to put a 160 therm in that has been proven to work. That way I have a lower threshold to do testing under. If I put a 160 in (and make sure the timing and tune is spot on) and it runs 180 or better, I can assume that I have a radiator issue cuz I have eliminated everything else. New Champion 4 core though. Would be a crying shame to have that be the problem. Will update again Saturday when I do the reseal.

 

Just a tech tip for the FE... drill a 1/8-inch hole on the thermostat flange and orient it at the 12 o'clock position upon installation to allow trapped air to bleed off when filling.

 

It looks like most of the possibilities here have been covered... I might add that you could completely remove the thermostat temporarily to see how hot it gets. While its off you could check the water flow by either peaking into the radiator with the cap off or even running for a moment with the upper hose disconnected. It should come out pretty fast. This is to check the new water pump for proper function. Another thing to check is how fast water runs through the radiator to make sure there are no manufacturing flaws; simply disconnect the lower hose and the water should drain pretty freely. You may have already accomplished much of this through your troubleshooting efforts up to this point.

One last thought I had that others could possibly provide their insights on is the head gasket installation. When rebuilding a 302, I learned the head gaskets must be oriented properly to ensure proper flow. The cheap gasket set I initially purchased didn't indicate how and I was getting conflicting information from the 302 forum page on FTE as to how they are to be oriented to ensure proper flow through the metering holes and such. Good FelPro gaskets indicate on the gasket itself how it should be installed making things kind of idiot proof; this is what I later purchased to ensure proper assembly. Now I have never had the heads off of a 390 before but from what I can tell by looking at online pics of the head gaskets and the short block, it looks like these could be installed on the wrong side if not properly marked. Improper flow can lead to an engine running hot.

I know you said its a trusted builder but we are all human. I hope this isn't the case but if you rule out all other possibilities, questioning whether it was properly assembled may become necessary.

I am sure someone else will chime in if I am wrong and this is a non-issue on the FE's.

 

"Need to do some more work and testing before I can answer that with more than an educated guess. I just put the engine in last weekend and was doing final adjustments and road testing when it crapped out the rear intake valley gasket stopping my day. Hate those cork P.O.S.'s. Going to pull the intake and reseal then start over with adjustments and temp testing."

Forget about using the "cork end gaskets". Go to the parts store and pony up for a tube of "The Right Stuff", or buy a tube of Black Permatex. Lay down a nice fat 1/4" tall bead all the way across the china walls from head to head. After the manny is torqued and the rtv set up, use a razor blade to trim any that squishes out the front if needed. I haven't used those cork suckers for years...