'80 F350, 2bbl, 400(z)

Working on this tomorrow so looking for advice/ideas before I get started.

Had truck for like 4 years and it overheats every year spring through fall.(anything over 70*). I originally thought it was just vapor lock but 99% sure it's the block overheating. I'm hoping it's not a head gasket but at this point I just want it fixed. Oil and coolant are not mixing, but I was told the head gasket can leak on the "exhaust side" and saw someone describing similar problems.

I've changed the gas cap like 3 times, flushed radiator twice, pretty sure I did the rad cap, changed the fuel pump 4(?) times, all fuel lines(vapor lock concern), changed the carb, distributor, timed it, and today I pulled the thermostat(changed at least 3 times) to make sure it was moving water-it was.

The other day I went out of town and cracked the hood to allow more flow while doing slow (5-10mph)driving and stopping but the gauge went up to the highest point in the safe range and stayed there. I got out of the truck and went to open the hood so it would cool while I was busy elsewhere. As I went to the front of the truck I heard PPPFFFFFFFFFFF, and when I popped the hood, the overflow hose was spewing water and steam into the reservoir. This hasn't happened since, but the truck always gets hot if I stop too long.
Also, because it gets so hot, I have a hard time starting as I'm sure the bowl evaporates after turning the truck off. Now I actually have to let it die on me 2-3 times before it will stay running or I have to tap the gas pedal a bunch of times and hold it lightly before it warms enough to stay running.

I'm going make sure the pump is pushing the right direction, and pull the spark plugs to see if there's coolant in there. The bottom of the engine from the lower pulley to behind the oil pan has moisture and I haven't gotten to the car wash yet. I keep getting little "puddles" of wet oil on the ground about where the axle runs. I'm going to double check the the oil plug because I just changed the oil and it's over a quart low already (I made sure the filter got full too).

Any other suggestions would be greatly appreciated.

 

Skrilla,

See if this helps you:

https://www.ford-trucks.com/forums/7...ssageways.html

 

pressurize the radiator and pull all the plugs and then listen for any water seeping in to a cylinder ! on the 400 the head gasket can go on both ways and if it is put on backwards it will cover up a water hole and will over heat real fast !
hows your fan and fan clutch and water pump ? on the radiator did you take it and have it rodded and flow tested ? or did you just flush out at home ? there could be lots of blocked tubes in the core and that would cause over heating !

 

I have a flex fan, bought the clutch but didn't realize I needed a different fan. Ran out of money then it got cold ... I may go ahead and get the fan. They always seem to say that flex fans have problems at high speed not idle...

Would this trick be ok to test the plug leak? ( I have a small compressor) (fast forward to 48 seconds)
YouTube - ‪How to Do A Radiator pressure test‬‏

I flushed it twice with the chemical stuff at parts stores. How can I check to see if the Radiator is clogged? I read about running a garden hose in it both ways. Do I need to remove the radiator or can I do it on the truck? What color will the deposits be if it is clogged?

Could the pump be rusting and missing one or 2 blades which allows -some- movement but not enough?

Gonna try this (free) stuff before ripping the heads off. -Thanks

 

i dont know how good that method will work , but give it a try but you will need to leave your hoses hooked up to the engine so put the shrader valve were the cap is , or you could take a old cap and drill a hole in it and put a tire valve in it ! put around 15psi in the system !
the flex fans are the worst thing as they do not pull the needed air through the radiator at LOW speeds so stop and go driving makes them worse ! get a stock fan with as many blades on it that you can find !
one way to check is to take a infrared thermometer and check the radiator at the bottom and top and middle , the one thing that gets clogged is the tubes with calcium and stuff and they are about impossible to get unclogged with chemicals , but you need to do what you can and any thing helps !
the water pumps can be missing ears , i have had a couple that the rotor was gone !

 

In general, a cooling problem while at speed is a coolant flow problem, and cooling problems in city stop-n-go driving are fan-related. In general.

I've read in the 335 forum about people converting to serpentine belt setups, but many don't realize they need different water pumps and fans - the impellers/blades on both are designed to operate awhile rotating in one specific direction.

Are you losing coolant? If not, I right now can't see the value in any leak tests but it never hurts to make sure, I guess, you can then at least eliminate that as a possibility.

I watched that video, I do something similar with gas tanks - I fill it with compressed air and watch for bubbles. Did it with my heater core, too. I don't get all complicated with valves and whatnot, I use an air nozzle, stuff it onto the neck, then seal it up with duct tape. It ain't perfect but it works good enough to see where the (other) leaks are.

Just a few squeezes of the nozzle handle are all that's needed to find air leaks but if you can find a way of measuring, I suggest going up to 2-3 times-max the designed operating pressure. IOW the cooling system is designed to operate at, what, 12-15 lbs I think. I'd feel comfortable going up to 40 or 50 lbs, try and force a leak.

40-50 lbs isn't so much that soldered brass is gonna bust open UNLESS there is already something in existence making a future leak imminent - corrosion in the process of making a hole, for example.

A redneck (free) way to see if radiator flow looks "good enough" is to drain it, then look down the filler neck while a garden hose fills it from the other side.

Thinking more about it, that'd require the hose be attached at the bottom, it'd leak all over the place. Duct tap to the rescue? (That's what I use when doing the air tests). I wonder where I read of this idea, I'm sure it was someplace on this forum.

In any event, feed one side and look down the neck of the other, you should see a good flow from the tubes into the tank.

If your heads have been removed then yes, as stated, the head gaskets can easily be put on wrong which will block flow to the heads.

For the evaporating-gas-from-the-bowl problem these exhaust-crossover engines have, look on summit racing and find a 2V version of the Edelbrock 8725 wood carb spacer (which I have). Wood provides EXCELLENT insulation from heat transfer to the carb; I remember hearing gas boiling in the bowl and white "smoke" coming from the bowl vent, aka smoke stack.

I don't remember the colors of the gunk & debris when using those flushing chemicals but I wanna say brown and maybe a greenish-white.

When I rebuilt my 400, I decided to get a brand-new radiator at the same time so there would be no question about its capabilities. The old one was "ok" and worked without problems but I just didn't feel comfortable spending a bunch of money on the total rebuild and using a 30 yo radiator with it. It's still in the rafters in my garage, maybe you can have it if it turns out your radiator needs help.

 

Forgot to mention, the M-block engines use a thermostat that also opens & closes a coolant bypass passage. I forget the details but you WILL have problems if you're using the wrong one.

Search the archives in the 335 forum, some guy had written a pretty good comparison & explanation and included pictures. All I remember right now is that Motorcraft & Stant are known to have the correct ones.

 

Borrowed a compression tester

100-|4-----8|-95
095-|3-----7|-100
093-|2-----6|-100
095-|1-----5|-92

Ran it to 5 clicks on the starter (about 5 seconds) as suggested by a Youtube video.

I had the porcelain crack off spark plug #5 and the wire ends stayed on plugs #4 and #3. I've changed the plugs 3-4 times and the wires 2-3 times. I think it might just be the overheating but I could be wrong (again lol). #4,6, 8 had a bit of crust on them (carbon?), 8 actually had quite a bit. The others looked good.

Earlier I noticed a little bit of smoke coming up behind the steering pump (by plug #5){Green circle} this area has oil or power steering fluid around it {red circle}


And it seemed to stop after I tightened down the lower power steering hose {purple}. This was a week or so ago and I still seem to be getting moisture on the bottom of the truck from somewhere. I'm not sure if it's oil or water, but there is oil in it (could just be runoff). There is a small puddle (drips) that form on blacktop about in line with the axle when it sits for a awhile.

Yes I have an Ozarka bottle as a temporary reservoir till I get this fixed lol.







I'm running without a thermostat atm.

 

The moisture would concern me; are oil & coolant mixing?

A poor-man's leak-down test: fill each cylinder with compressed air, then look for bubbles in the radiator/listen for air in the carb/exhaust/oil filler.

A friend of mine has a compression tester we use for this test, the gauge removes from the hose and the hose can then hooked to the air compressor. Bring a piston to TDC on the compression stroke, then put about 50 lbs pressure into the cylinder.

A manual transmission is great here, you can put it into gear before putting air in, this keeps the air pressure from pushing the piston down and turning the rotating assembly.

I have that same kind of leak from my front axle area (81 F350) I figure I'll deal with the axles and ball joints "one of these days soon."

I'm assuming the problem exists without the thermostat installed, correct? Which would mean a wrong thermostat isn't the problem.

Your compression numbers are kinda low but they're all close to each other, that's a good thing.

The crust on the plugs concerns me, I'm thinking it could be from water. What color was it?

 

It was a whitish tan kinda like a good burning plug tip. I'll look again.

A guy at the parts store where I was picking up the compression tester was talking about the "Bring a piston to TDC on the compression stroke, then put about 50 lbs pressure into the cylinder" test.

How do I set each cylinder to TDC? I did it when I was timing(been over a year), but is there a quick trick for it (how do I know WHICH cylinder is TDC)? I've got it torn apart right now and headed back out to beat the rain or I'd search around the net. The plugs are still out and they said I can keep the kit through tomorrow.

Currently have the radiator off, yanked the AC rad (permanently since it never worked or bothered me) and trying to take the AC compressor(?) off the block (this has never even had a belt on it since I've had the truck). It's empty, just want it gone so I don't have more to worry about being in the way. The AC rad had walled over fins in a few spots so glad that's gone.

Ran garden hose through all 3 holes till water came out clean slushed it around good. 2 of the hoses had rust/nasty water in them, but the pan I emptied into looked OK. Atm I have some lime away in it neighbor gave me, then another good rinse.

The rust was very minor and I only knew what it was by putting a magnet in the water bucket.


I just pulled the Thermostat off, so I'm not sure if it alleviated the problem, though the little I ran it today, it obviously ran cooler.

 

This 50-lbs-pressure-in-each-cylinder test (AKA leak-down test but not measuring percentage losses here so not so precise) basically just stuffs air into a "sealed" combustion chamber and then looks for leaks.

It'll require the radiator be hooked up and water be in the cooling system.

You test each cylinder, one at a time.

A remote starter switch is a GREAT help here, should be less than $20 at auto parts stores or you can improvise and use a small piece of wire.

Jump 3 & 5 to cause the starter to crank the engine. Just bump the starter while you put your thumb over the target cylinder's spark plug hole, crank it until you feel pressure on your thumb, bump it 'til the piston gets to the top.

From Franklin2's pictures:


Ideally, you want the piston as close to top-dead center as possible but it doesn't need to be exact, we just need both the intake & exhaust valves to be closed (which they are at TDC).

If an auto transmission, it needs to be more exactly at the top as the air pressure is gonna want to push the piston back down; if a stick, putting it into gear will keep the engine from turning.

A 15/16ths ratchet on the front dampener pulley can be useful in rotating the engine, too.

Connect the air hose, put about 50 lbs of pressure in, then look & listen....

Air bubbles in the radiator indicate a blown head gasket; air coming up through the carb is a leaking intake valve; air in the exhaust pipe is a leaking exhaust valve; air coming through the oil fill cap is leaking past the rings.

In this case, we'd be most interested in the bubbles in the radiator; water in the combustion chamber would be the source of a loss of coolant, white "smoke" from the exhaust, the cause of fouled plugs, and a lack of pressure in the cooling system.

Ya know, I have that exact same engine, it's a shame you live so far away, I'd be interested in taking the factory AC off your hands.

 

The hose from *my* compression tester has got a check valve built into it, this keeps me from using it to put air into the cylinders. But my friend's doesn't so we use that.

Just something to watch for, you might be able to rent a real leak-down tester someplace.

 

I did the pressure check as best I could (time limit on tool), everything seemed to go ok until I got to the last one (figures). There were no bubbles in the radiator, I didn't really check for the others because I must have skimmed the post too quick (oops) but I think one may have come through the carb and one through the oil. Again I was on a time limit so I may have messed up the test.

Usually when I would put the pressure on, the fan would spin a little so I may have missed the spot, but I redid a few to be sure, I was mostly checking for bubbles.

Anyway, my main concern is that when I was doing #6
|4-----8|
|3-----7|
|2-----6|
|1-----5|

Air was coming out of #5. Is this a warped head or gasket.... or nothing? lol.

As for the AC, you can have it once I get a little $$ together for shipping (low on funds atm).

 

You mean air was coming out of #5's spark plug hole?

I would want to verify the test by re-doing it, ensuring the piston is at the top. Those two cylinders are right next to each other in the firing order:

1-3-7-2-6-5-4-8

 

Indeed. We did this one twice. It was the last one so I went back to the book to check the firing order ( I was hoping it might have just been slightly open on both if that's even possible), but it had a steady but not strong flow of air in the hole.

I think this happened, I wanted to try again, I spun the engine around till we got air pressure on the cylinder again, and then it didn't so we adjusted and then it did again. I checked this because I felt some air on my arm. I checked plug #7 and no air.

This is an automatic and I just had it in park. When I put the air through it, it would kick the fan a little or a lot. I wasn't sure how to make sure it was 100% TDC so I just figured this was straightening it out....?


Cracked/warped head, or just some strange occurrence?

I took the tool back earlier, but I can try to get it again.