Author Topic: 428 overheating at idle  (Read 5069 times)

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happystang

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428 overheating at idle
« on: February 17, 2019, 02:07:22 AM »
I'm on the second rebuild of my 428, the first build lasted about 200 miles before a rod bearing self destructed. During that span, the motor ran great with temps ranging from 185-195.

It's now overheating at idle after being rebuilt a second time and I'm losing my mind trying to figure out the cause. The moment I bring the RPM up, the tempture shoots down, cruising its stone cold. I'm using a mechanical water temp gauge. EVERYTHING is the same as it was on the prior build, same timing, carb tuning, clutch fan, water pump etc. I'm running a Derale clutch fan with a factory shroud and ACP 3 row aluminum radiator.

The second rebuild consisted of new bearings, rings, hone, and crank regrind (and new gaskets of course). The machine shop built the short block, I assembled the rest. I purchased the exact same gaskets as before. I never pulled the thermostat, it's the same one that was in the motor before the second rebuild.

The head gaskets are not backwards and I did a block test to verify that there aren't combustion gases getting into the cooling system.

With the cap off, I can see coolant flowing when the thermostat opens. I've tried moving the initial timing anywhere from 8-22 degrees with no change, I left it where it ran best around 14. I even removed the PCV just to see if it was sucking in too much air and making it run lean at idle, again no change.

The only change is from a standard volume up to a high volume pump and the addition of oil restrictors in the cylinder head for the rocker arms (I'm using a massive Canton oil pan).


What gives? At idle it creeps up past 215+, but when the RPM's increase or I begin cruising it's 175-180.

machoneman

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Re: 428 overheating at idle
« Reply #1 on: February 17, 2019, 08:07:47 AM »
Change the t-stat. Drill 1-2 small holes in the perimeter area first (say 1/32). Fill. Jack the car up about 1' to ensure any trapped air bubble goes away. Run it till hot, heater on. You may have a hot spot due to air in the cooling system.
Bob Maag

Drew Pojedinec

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Re: 428 overheating at idle
« Reply #2 on: February 17, 2019, 09:40:32 AM »
Overheat at idle.  No issue at all once rpm's come up and car moves?

I think my first thing to look at would be the clutch fan locking up sufficiently.

shady

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Re: 428 overheating at idle
« Reply #3 on: February 17, 2019, 11:35:56 AM »
I'd put some miles on it & see what happens.
What goes fast doesn't go fast long'
What goes fast takes your money with it.
So I'm slow & broke, what went wrong?
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C8OZ

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Re: 428 overheating at idle
« Reply #4 on: February 17, 2019, 11:42:02 AM »
At that temp, if the fan clutch is working right, you should feel a heavy blast of very hot air behind the fan. No big wind, the clutch isn't locking. Big cool wind, there's a coolant flow issue.

My427stang

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Re: 428 overheating at idle
« Reply #5 on: February 17, 2019, 11:49:14 AM »
How many miles on the new motor?  Sometimes a tight fresh engine with old school high tension rings and a fresh crosshatch can be a little warm, but a day of driving should loosen things up

Like others have said, I'd check the fan close, and maybe swap the thermostat and drill a single small hole at 12 o'clock.

Also, not sure how the heater works on the car, but if it's a on/off valve like on the pickups, open the valve and let the hot water circulate, it should purge any air above the thermostat

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Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

wowens

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Re: 428 overheating at idle
« Reply #6 on: February 17, 2019, 02:21:07 PM »
No airflow through radiator at idle . I think something has gone wrong with the fan clutch.  If it proves out I'm wrong it will only be the 11,236th time.
Woody

plovett

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Re: 428 overheating at idle
« Reply #7 on: February 17, 2019, 02:47:04 PM »
Agreeing with everybody else.  Hot at idle, but fine at higher rpm points to an airflow issue.

JMO,

paulie

plovett

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Re: 428 overheating at idle
« Reply #8 on: February 17, 2019, 02:49:51 PM »
I know you said everything is the same, but are you using the same pulley on the water pump and crank?  Underdrive pulleys can do what you are describing.

paulie

happystang

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Re: 428 overheating at idle
« Reply #9 on: February 17, 2019, 05:51:08 PM »
Thank you all for the suggestions. I have about 15 miles on the motor but several hours worth of run time at idle.

Today I tried a new 180* thermostat with a hole drilled in it along with adjusting the time timing. The fan clutch still has plenty of drag, it's a Murray 2711 and I can feel it blowing air at idle. The fan will even suck a piece of paper to the front of the radiator and hold it there at idle.

The pulleys are the factory units that I had on the prior rebuild.

I'm officially stumped.

My427stang

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Re: 428 overheating at idle
« Reply #10 on: February 17, 2019, 06:42:36 PM »
If it doesn't boil over, run it a bit.  215 may be different, but it's not too hot under pressure. 

15 miles and no load idle isn't much, not saying what you are seeing is common place, but if big 5/64 3/32 ring pack, standard tension oil rings and a coarse hatch, they can build some heat.

If it were mine, and it's behaving normally otherwise, I'd get some miles on it and see what it does.   

BTW, lean idle doesn't make a 4 stroke run hot at idle, retarded timing, poor airflow, air bound, etc sure does.  Any chance you are doing something accidentally like setting initial with the vacuum advance hooked up?
« Last Edit: February 17, 2019, 06:44:15 PM by My427stang »
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Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

wowens

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Re: 428 overheating at idle
« Reply #11 on: February 17, 2019, 07:03:30 PM »
How long between builds ?
Woody

shady

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Re: 428 overheating at idle
« Reply #12 on: February 18, 2019, 09:09:06 AM »
I once had a mouse build a nest in the radiator while it was pulled out over winter. Couldn't see it until it let loose.
What goes fast doesn't go fast long'
What goes fast takes your money with it.
So I'm slow & broke, what went wrong?
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BigBlueIron

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Re: 428 overheating at idle
« Reply #13 on: February 18, 2019, 04:13:30 PM »


The head gaskets are not backwards and I did a block test to verify that there aren't combustion gases getting into the cooling system.


A backwards head gasket will not necessarily push combustion gasses into the coolant. It just blocks flow.

 I would verify they are correct, it is easy to get one backwards (I've done it) especially since some gaskets are a different color on each side say blue on one side black on the other, messes with a persons head that one would be flipped over to be in the correct position. This can be done with a quick visual check. http://www.fordfe.info/Forum/FAQ-Style-index2.html#HeadGasketInstall or https://www.ford-trucks.com/forums/1118889-overheating-issue-after-engine-tear-down.html

Sorry for posting from FTE but the description and photos are excellent. Rare to actually see correct info on that site.

machoneman

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Re: 428 overheating at idle
« Reply #14 on: February 18, 2019, 06:15:53 PM »


The head gaskets are not backwards and I did a block test to verify that there aren't combustion gases getting into the cooling system.


A backwards head gasket will not necessarily push combustion gasses into the coolant. It just blocks flow.

 I would verify they are correct, it is easy to get one backwards (I've done it) especially since some gaskets are a different color on each side say blue on one side black on the other, messes with a persons head that one would be flipped over to be in the correct position. This can be done with a quick visual check. http://www.fordfe.info/Forum/FAQ-Style-index2.html#HeadGasketInstall or https://www.ford-trucks.com/forums/1118889-overheating-issue-after-engine-tear-down.html

Sorry for posting from FTE but the description and photos are excellent. Rare to actually see correct info on that site.

My 1st thought as well!
Bob Maag

dmann

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Re: 428 overheating at idle
« Reply #15 on: February 18, 2019, 09:55:37 PM »
I have an old Volvo that I recently put a new fan clutch on.  I switched to the "heavy duty" version of the clutch, but I think what I'm about to tell you is something to consider.

The old fan clutch seemed to work fine and also had plenty of drag, but I was replacing all of the cooling system parts so I went ahead with it.


When the car has been idling in traffic on a warm day at a stop light, the sound that the fan makes as I take off is very very noticeable.  The fan is exactly the same, the only difference is the clutch.  It sounds like a truck.  It moves that much more air.

If your vehicle is hot and you can't hear the fan really moving the air when you rev it (more air movement than when it was cool), then maybe the clutch is toast or it's not getting hot enough to activate.  My fan clutch needs to get pretty hot.  I don't have a temp gauge with degrees on it (it's factory), but it needs to really get warm before it really wakes up.

Once up to a decent speed the fan quiets down on my Volvo - and I believe that exactly how it was designed to work.  Driving gives enough airflow through the radiator that the clutch cools off (along with the coolant) and the clutch becomes free wheeling (or closer to it).

Is your radiator getting as hot as the engine itself?  Can you get a BBQ temp probe into the fins to see what it is reading?  The coolant on the hot side of your radiator really should be close to what it's running at near the temp sender in the engine.  If the radiator isn't getting hot that's a big problem.

I hope you find the issue, best of luck.

Leny Mason

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Re: 428 overheating at idle
« Reply #16 on: February 27, 2019, 08:51:15 AM »
Hi, on my 1969 428 Mustang I built in 1976, a few years ago it started to over heat in parades, as we where getting ready to go to the International Mustang Meet in Calgary Canada, I was looking everything over when I grabbed the water pump fan it was ready to fall off lucky, I put a water pump on that night we left in the morning, it has not heated up in parades at all, try a new water pump if you can. Leny Mason

Stangman

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Re: 428 overheating at idle
« Reply #17 on: February 27, 2019, 09:06:38 AM »
Whatever happened happystang is it happy yet. 8)

happystang

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Re: 428 overheating at idle
« Reply #18 on: March 02, 2019, 10:52:02 PM »
Hi everyone!

I've been down in Southern California for school and haven't had a chance to make the 300+ mile drive to work on the 428. I'll be back home in a couple weeks to screw around with it :). I've ordered a couple different fan clutches, hopefully one of them will work/continue to work!

If all goes well, I'll be bringing it back down with me for the rest of the semester (and the Fabulous Fords Forever show in Anaheim).

IMG_8876 by armon7, on Flickr

happystang

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Re: 428 overheating at idle
« Reply #19 on: March 17, 2019, 10:53:58 AM »
Okay guys, just following up- the overheating issue seems to be solved.

The replacement heavy duty Hayden 2765 fan clutch seemed to help a little bit, but the temperature still eventually crept up. I added some Water Wetter as a last ditch effort and maybe got a 2-3 degree improvement, but again the car would eventually get hotter than I'd like at idle. I ended up ordering a 17" high output Derale electric fan and a SPAL thermal relay kit. SPAL includes both a 30 and 40 amp fuse in their kit along with eyelet connectors, a fuse holder, all the wiring, thermostatic switch, and a bunch of other bits and pieces. The fan pulls around 23 amps- I found that the initial power spike on fan startup was too high for the recommended (per Derale) 30 amp fuse, so a 40 amp fuse was used instead. I attribute this to ditching the low speed setting and wiring the fan so that it immediately goes to high speed. The fan kicks in at 195* and shuts off at 185*. Problem solved!

The fan is off almost all of the time and only comes on at idle when needed. It's significantly quieter than the mechanical fan and I don't have to worry about losing any fingers. One thing I did notice however is how difficult it is to get hot air OUT of the engine bay as it takes longer for the fans to bring the temperature down with the hood closed. I'll try and get some pictures of the setup later today.

I took the fastback on a rather arduous cruise with a few mustang buddies yesterday and she ran flawlessly!

IMG_1865 by armon7, on Flickr

IMG_1897 by armon7, on Flickr

Faron

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Re: 428 overheating at idle
« Reply #20 on: March 17, 2019, 11:19:20 AM »
Do you have the water pump over or Under driven , All Fords are Over driven when they had AC , that being said I changed to an over driven water pump on my blown combo and it dropped almost 15 degrees at slow speeds , obviously you had an airflow problem , but spinning the water pump fan combo may have solved it as well

Bolted to Floor

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Re: 428 overheating at idle
« Reply #21 on: March 17, 2019, 01:26:11 PM »
Due to the tight compartment, big engine, and lots of heat......I opted for the 67 Shelby hood with scoop and “fish gills” on the sides. The gills do allow for a lot of hot air to escape. The gills will allow for water into the engine compartment on rainy days or wash days, if you are worried about that.

Others have made changes on the hood hinges to create an opening at the back of the hood for hot air to escape. I don’t remember if they stacked washers under the hinge bolts or something else. Someone should chime in.
John D -- 67 Mustang 390 5 speed