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First start of rebuilt engine and it runs hot

eBronc2

Contributor
Jr. Member
Joined
Jan 10, 2015
Messages
189
https://doc-00-4o-docs.googleusercontent.com/docs/securesc/8o60mm2tnl2f2j8rc9rjcoisli8e0bpr/ph8kqqeespscujf1uilgodi89uf5nel8/1465783200000/00280514287852618659/00280514287852618659/0B9d5da_Xfl_ganFMTGhmVUowc2M?e=download

I rebuilt a 351W I pulled from a junkyard years ago, it's sat for years until I finally got it onto the chassis and rigged up (hooked up a battery, electric fuel pump, MSD box, aluminum radiator with fan blowing through it, etc) to start up and get it run in before I put the body back on the chassis. I converted it to serpentine drive, made sure I put the correct water pump on (driver's side lower inlet), and installed a BeCool aluminum radiator and 180 degree thermostat. No engine fan, using shop fan on high blowing through radiator for testing.

Got it started with no real problem (built up oil pressure before starting it), had the timing set as close to O as I can tell, made sure firing order was correct, plenty of oil, etc - but the water temp climbs quickly past 180, 190, 200 - when it passes 220, I shut it off.

Let it cool, checked the hoses to make sure they weren't collapsed or blocked, pulled out the thermostat, flushed the radiator, checked the oil, put everything back together, and tried again. Starts right up, sounds good, but again water temp climbs right past 200 and keeps going, so I shut it off.

I checked for water flow through the radiator with the cap off just after it started, it's flowing fine. Good oil pressure. Carb is a Qjet that was rebuilt years ago and not used until now.

Either I've got some kind of weird blockage in the cooling system(I doubt since I see good water flow through the radiator), the ignition timing is way off (possible, since the timing tab is original and the dampener is aftermarket, but it can't be too far off since the engine fires right up and runs well), or the carb is jetted really lean (very possible, since I can't even recall what the carb originally came out of. Still, it would have to be EXTREMELY lean for the engine to get this hot, this quick. It got hot enough for the plastic spark plug wire looms to start melting.

I need to get a good timing light and verify the timing, and get an air-fuel ratio sensor and gauge (I put O2 bungs in the exhaust for future EFI), and see how bad the carb is jetted.

Any ideas?
 

Nickm1024cobra

Sr. Member
Joined
Jun 15, 2014
Messages
362
Loc.
Chicago Burbs
https://doc-00-4o-docs.googleusercontent.com/docs/securesc/8o60mm2tnl2f2j8rc9rjcoisli8e0bpr/ph8kqqeespscujf1uilgodi89uf5nel8/1465783200000/00280514287852618659/00280514287852618659/0B9d5da_Xfl_ganFMTGhmVUowc2M?e=download

I rebuilt a 351W I pulled from a junkyard years ago, it's sat for years until I finally got it onto the chassis and rigged up (hooked up a battery, electric fuel pump, MSD box, aluminum radiator with fan blowing through it, etc) to start up and get it run in before I put the body back on the chassis. I converted it to serpentine drive, made sure I put the correct water pump on (driver's side lower inlet), and installed a BeCool aluminum radiator and 180 degree thermostat. No engine fan, using shop fan on high blowing through radiator for testing.

Got it started with no real problem (built up oil pressure before starting it), had the timing set as close to O as I can tell, made sure firing order was correct, plenty of oil, etc - but the water temp climbs quickly past 180, 190, 200 - when it passes 220, I shut it off.

Let it cool, checked the hoses to make sure they weren't collapsed or blocked, pulled out the thermostat, flushed the radiator, checked the oil, put everything back together, and tried again. Starts right up, sounds good, but again water temp climbs right past 200 and keeps going, so I shut it off.

I checked for water flow through the radiator with the cap off just after it started, it's flowing fine. Good oil pressure. Carb is a Qjet that was rebuilt years ago and not used until now.

Either I've got some kind of weird blockage in the cooling system(I doubt since I see good water flow through the radiator), the ignition timing is way off (possible, since the timing tab is original and the dampener is aftermarket, but it can't be too far off since the engine fires right up and runs well), or the carb is jetted really lean (very possible, since I can't even recall what the carb originally came out of. Still, it would have to be EXTREMELY lean for the engine to get this hot, this quick. It got hot enough for the plastic spark plug wire looms to start melting.

I need to get a good timing light and verify the timing, and get an air-fuel ratio sensor and gauge (I put O2 bungs in the exhaust for future EFI), and see how bad the carb is jetted.

Any ideas?

Ive had plenty of 302's. Have a 408W in another vehicle and it idles for about 20minutes before the electric fan even kicks on. Quality radiator in that car.

Had plenty of other 302w/351 motors as well with limited cooling issues.

Move on to my bronco build. With no fan hooked up that thing went to 220 in an instant with a nice aluminum radiator. Hooked up the mechanical fan (explorer fan) and it took a little longer but got hot enough to shut it down. Installed the fan shroud and finally it will stay under 210. Dont know if it is the tight space of the engine bay or what in these broncos.

My recommendation, make sure that the timing is spot on. Believe they like atleast 10btdc to get in the ballpark and go up from there. Check the temp of the headers with an infrared gun. That should give you an idea of lean condition or timing issue. Rule those out and Verify you have the correct rotation water pump. Thermostat a 180? Last i would make sure all air out of system. I generally fill radiator, then unplug a hole in intake and fill it there as well. By doing so i generally can get moist air out. Good luck.
 

68stang73

Sr. Member
Joined
Nov 29, 2015
Messages
399
Get the explorer fan on it or your asking for trouble. Then get a timing light on it. If stock cam 8-12 degrees with vac advance plugged. If headers were glowing then you know for sure it's running lean. Pull plugs and peak at them. If so fatten up the air fuel screws.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,275
What Nick said about the timing. You can't continue to run it near zero and expect it to run cool.
I realize that you don't actually "know" that it's zero, but you need to at least experiment with advancing the timing to make sure that's not the issue.
Too bad you didn't mark things when you had it apart to know where TDC actually was, so you could reference it from then on. That's pretty much a must do with Fords these days.
Otherwise you're just guessing unless it's all original.

And just having the water pump inlet on one side or the other does not make it the correct pump. Reverse flow or standard flow are to match whether it uses V-belts or is serpentine. Different standard rotation pumps are available with inlets on either side. Not sure about serpentine reverse flow pumps, but it at least holds true for standard.
So you could easily have the wrong pump for a serp setup.
The pump has to match both the front cover AND the belt rotation direction.

Or maybe not, since it sounds like you got lucky on this one.
The good news is that it sounds like this isn't a coolant flow issue, as you said you can see fluid flowing well in the radiator. Even those with good pump setups can't always claim that!

There's also the infamous head gasket on backwards scenario that could be cropping up. Since you did the build yourself, do you know for sure that those are on correctly?

And check the gauge against another source, such as an infrared thermometer pointed directly at the intake next to, and on the water temp sender. This might give you some clues, or might not. Depends on what you get so it's a worthwhile test.

And like was said, making sure the air flow is good is a key. Shroud, fan direction (you do have a reverse rotation fan, correct?) are good places to start also.

Good luck.

Paul
 
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eBronc2

eBronc2

Contributor
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Jan 10, 2015
Messages
189
I sure wish I would have fired it up after I had rebuilt it years ago, at least all the build details would be fresh in my mind. I do remember finding the right timing cover was a challenge, since it needed to have the water ports angled the correct way to match up with the reverse rotation water pump, no mechanical fuel pump pad, no dipstick, and no crank sensor hole.

After doing quite a bit of reading, I think the timing is heavily contributing to the overheating - everything I can find for an '84 351W shows the initial (base) timing should be around 10 degrees advance. When I set the timing before startup, I removed the #1 plug, rotated the engine until both valves on #1 were closed, checked for compression in #1 cylinder, and slowly brought the piston up to TDC, using a small screwdriver through the spark plug hole against the top of the piston to feel it's travel. Once it was at TDC, I rocked it back and forth slowly to make sure, and verified the 0 degree mark on the aftermarket balancer lined up with the timing tab, the distributor rotor lined up with #1 tower on the cap, and the spoke of the reluctor wheel lined up with the hall effect sensor in the base of the distributor. I'll move it to 10 BTDC (static) and pick up a timing light to check it while it's running.

I removed the thermostat to check it, to make sure it was installed the right way, and to verify it was a 180 degree. I left it out when I fired the engine up the second time, it got just as hot just as quick, so that pretty much rules out the thermostat as the problem.

The air fuel ratio could be lean, the Qjet was rebuilt but not modified, with the aftermarket cam, shorty headers, and Edelbrock intake the engine is most likely flowing significantly more air than whatever stock engine the Qjet was originally on. I do have a fuel pressure regulator and gauge in the fuel line, but the I suspect the old, cheap gauge is not working correctly, I have to tap it several times to get the needle to move, and it won't show any higher than about 2 psi no matter how much I adjust the regulator. Fuel pump is a new Holley electric, so pressure and volume shouldn't be a problem. I know Q jets like 3.5 - 4 psi, so once I know the carb is getting the right pressure I can move on to changing float level, primary metering rods, and jets, etc.
 

blubuckaroo

Grease Monkey
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Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
One of the things that seems to be a reoccurring problem is incorrectly installed head gaskets.
I think the problem is when we are assembling the motor, we like to see the gaskets with the same side up. But since the gaskets are both the same, it's correct to have one flipped over.
If the head gasket is installed incorrectly, the coolant will bypass the head, and still show circulation through the radiator.

Another assembly mistake that seems to reoccur is installing the thermostat backwards.
The results here, will be a cycling high and low temperature, as the thermostat will eventually open, but close again as soon as the cool water gets to the sensor pellet.

There also seems to be a difference when filling the 351W from the other small block Ford engines. The 351W can take extra steps to purge the air out of the manifold. I've had to remove the rear manifold plug to get the air out of one.

Good luck with this and keep us posted!
 
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eBronc2

eBronc2

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Found a couple of things wrong, had to do some testing to track them down. Both the old, cheap fuel pressure gauge and the new electric fuel pump were not working right, I bought a quality Autometer pressure gauge to check and the new pump was only putting out about 2 psi.

I dug up an old Holley "red" electric pump I had laying around, cleaned it up, put on some fittings and hooked it up. It puts out a consistent 6 psi, so I used that and brought down the pressure with the adjustable regulator to about 5 psi, the carb and engine seemed to like that a lot better.

Once the new timing light showed up (gotta love Amazon Prime), I set the base timing (idle, vacuum advance disconnected and plugged), to 12 BTDC.

When I refilled the cooling system, I removed the allen plug on top of the thermostat housing (90 degree housing) to let out trapped air in the block/heads/manifold, slowly added water until it started to flow out of that opening, put the plug back in, and added more water until the radiator was full. One thing I found that may be a problem is the radiator cap is only rated at 7 psi, the BeCool radiator works best with a 14 psi cap (according to their website), so a new cap is on the way.

Fired up the engine and it runs quite a bit cooler, at idle or high idle it will stay around 200-210, if I increased the rpm to about 2500-3000 where I needed to have it for the break-in period, it would warm up to 220 or so but didn't boil over, so I ran it for 30-45 minutes at various rpm points to break in the cam and check for leaks, kept an eye on oil pressure, fuel pressure, voltage, and used an infrared thermometer to measure the temps of the header tubes about 2 inches away from the head flange - most were in the 500 degree range, there was some temp differences between cylinders but I'm sure I still have some carb tuning to do.
 

partsloco

Sr. Member
Joined
Jun 15, 2004
Messages
405
Yeah, I'm thinking head gaskets too. If you checked everything else and your timing is 10-16 BTC. I have had gauges go bad.
 

partsloco

Sr. Member
Joined
Jun 15, 2004
Messages
405
Engines do run hotter when your breaking them. Seating the rings creates lots of friction. That's why they say don't break in an engine with ceramic coated headers.
 

rydog1130

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Jun 19, 2014
Messages
4,019
Engines do run hotter when your breaking them. Seating the rings creates lots of friction. That's why they say don't break in an engine with ceramic coated headers.

Sorry to high jack this thread but just a quick question. If I'm only getting my heads redone is it ok to run ceramic headers on it still? I'm assuming yes since I'm not putting new piston rings in it
 
Last edited:

DirtDonk

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Nov 3, 2003
Messages
47,275
Yes correct. The main engine break-in procedure that we always talk about upon first fire up, is for the camshaft break in. Not the general rings and other stuff.
But all that other stuff is important too. Just that the cam break-in is the real critical one with any flat-tappet cam.
Not a big deal with roller cams anymore.

You should be good to go as you don't have to break in anything unless you changed the lifters and/or cam too.

Paul
 

ntsqd

heratic car camper
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Jan 30, 2005
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3,214
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Upper SoKA
I always drill and deburr an 1/8" hole in the t-stat's flange. I place it close to the edge of the gasket. On engines with it flat (SBC's, 22R's etc.) I don't worry about orientation, but with SBF's, slant 6's etc. I place the hole at the top. Makes the system self-bleeding of air.
 

68stang73

Sr. Member
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Nov 29, 2015
Messages
399
If your cam is bigger than stock it might like more timing. Maybe even 16 degrees . My mustang is at 21 with 36 total. Also make sure your total isn't too high. She will run hit at cam break in just as well as running hot if it neefs more timing.
 

blubuckaroo

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11,795
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Ridgefield WA
I just re-read your initial post. Am I correct that you are using a shop fan to blow through the radiator?
No way would that be enough air. Even if you were to build a duct for it to direct it.
 
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eBronc2

eBronc2

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I let it sit for a few days while I was out tubing down the river on vacation, when I got back I re-torqued the heads and intake (broke loose, then torqued to spec one bolt at a time using the torque pattern). finally found my Q-jet idle mixture screw adjusting tool and set both screws to 5 turns out, set base timing to 12 degrees BTDC, replaced the old, 7 psi radiator cap with a new 14 psi cap, and hooked up a valve cover breather to use as a PCV.

No more overheating problem, runs smoother, able to set idle speed down to 900 rpm and no more melting plug wire dividers.

I'm using the factory Duraspark distributor, the vacuum canister is hooked to a port on the carb that should be ported vacuum, but it has vacuum even at idle speed (less than 1000 rpm), and the throttle blades are closed. Base timing with the vacuum hose disconnected and plugged is 12 BTDC, but with the vacuum hose hooked up is 34 degrees, even at idle. Engine idles much smoother and happier at the indicated 34 degrees. I need to do some more testing with the timing light and verify advance at different rpm points to make sure the vacuum advance is dropping out and centrifugal advance is coming in when it should.
 

DirtDonk

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47,275
Glad it's running better. All that timing is just what it seems to like at least initially anyway.

If it's a ported fitting on the carb, you should still be able to see it drop as you push on the pedal, but it's likely the high idle (1000 rpm) that is putting the throttle plates just above the timed port for that fitting.
Or you could try the other tube fitting. Most carbs have at least one of each, and Q-jets often have hundreds! Ok, well, at least three.;)
Should be easy to find if one or the other is off at idle, but I still think that idle speed is high enough to be getting the blades just above where they start to open the port.

Good luck. Keep on fiddlin'

Paul
 
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