Boiling Coolant When The Engine Is Turned Off.

D

Don Norton

Member
I have run into a little issue here. I have a SB Chevy 407, Aluminium heads, Z28 intake. I set the compression at 10.5:1, Timing is set at 6 degrees BTDC, MSD Atomic EFI and the A/F ratio is set at 14.7, Flex Lite 429 dual fans that are controlled by the MSD Atomic EFI controller ( Fan 1 ON @ 182, Fan 2 ON @ 187). 180 thermostat. 50/50 mix anti freeze (orange) Prestone. Running down the road I have no problem maintaining the desired 180 degree engine temp. But, when I stop and turn the motor off the next thing you know the coolant temp spikes to 230 -250 degrees and boils the anti freeze. I now have gotten into the habit of allowing for a cool down period before shutting the motor off and that seams to prevent the problem. I'm looking the the Flex lite dual fan controller that allows the fans to continue to run after the motor is shut off.

The other thing that has been bugging is the head gaskets. I'm using the Fel-Pro MLS 144053. I noticed that they only had steamer holes on the upper section of the gasket and none on the lower section. I call Fel-pro and questioned them about it. They said the steamer holes we're not needed on the lower section because of the design of the gasket. I still question this. I think I should of gone ahead of drilled steamer holes in the head gaskets. What's your thought on this?
 
reading this linked thread (below) may help
adding some water wetter to the coolant might help
Water-Wetter.jpg


personally,
Id read the linked thread and add the coolant steam holes

http://garage.grumpysperformance.co...-steam-holes-posted-by-dennyw.2991/#post-7851

if the car runs down the road and maintains a 180f temp but if its sitting at idle and over heats it may need a more effective fan/fan shroud combo, and I certainly would consider adding a larger capacity radiator at some point

heres a couple more related threads
, ID point out that adding an effective oil cooler and a 7-8 quart baffled oil pan,
can at times significantly reduce engine temps

http://garage.grumpysperformance.com/index.php?threads/choosing-an-engine-oil-cooler.15375/

http://garage.grumpysperformance.com/index.php?threads/choosing-an-engine-oil-cooler.15375/

http://garage.grumpysperformance.com/index.php?threads/do-i-need-the-fan-shroud.13847/#post-70867

http://garage.grumpysperformance.com/index.php?threads/thoughts-on-cooling.149/
 
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Just started this or all along? Fans pushing or pulling the correct way? Water pump impeller came loose?
 
Is it possible that the battery may be weak. You state that it stays cooler while running, and spikes when engine is off. That tells me that the alternator is putting out enough juice to keep the fan spinning fast, and when you shut the engine off, you are running on battery alone. The battery might not have enough juice to properly spin the fan fast enough. Just a thought.
 
The fans are mounted on the engine side of the radiator and pull through the factory oil cooler, tranny cooler and A/C condenser. I'm using a 100 Amp alternator and a Red Top Optima battery. Battery is in good shape. # 8 wire feed the fan relays. The MSD Atomic controller is controlling the fans ( Fan 1 ON @ 182 Off @ 172, Fan 2 ON @ 187 Off @ 177). Only thing I don't like is the fact that when shut the motor off, the MSD Atomic controller stops the fans, no time delay Off. That's why I'm looking at the Flex-a-lite dual fan controller. It'll run the fans for 20 to 30 seconds after the motor is shut off. The water pump is a brand new with a 8 blade impeller. Radiator is aluminum fat 2 core, plastic tanks. (I'll test the radiator cap, which is new). I'm using a 5 qt factory oil pan with trap doors. It takes about 7-8 qts to fill the oil system, dry. 6 qts on a normal oil change. I'm kind of pointing my fingers at the aluminum heads. They are Skip White NKB-272-SH. They do have the steam hole drilled in them. Unlike all the other heads that I looked at. Did not have this problem with the old cast iron fuelie heads but the compression was down around 8.5 to 9:1 on the old motor but they are iron which don't absorb heat as fast as aluminum. The new motor is sporting a 10.5:1 compression, 5.7 rods, KB Hypereutectic pistons, Eagle crank, Comp Cams roller cam 12-422-8 (I = .495 lift, 270 duration, Exh. = .502 lift 276 duration), Comp Ultra Magnum 1.5 roller rockers, Mellings high volume oil pump, 10w -30 Valvoline High mileage synthetic oil.
 
Do you have an electric water pump to circulate the coolant when engine is off? I only ask because you said you do a cool down before you shut off the engine. Without an electric pump, the fans would only cool the fluid in the radiator because of no circulation. I had a heat issue with my truck a few years ago, and discovered an air pocket above the thermostat. I made a bleeder to evacuate any trapped air in the system. This may not be your issue, but I thought I would mention it. If the steam holes are blocked, I can see that being an issue too.

Nice engine combo by the way!
 
Don Norton said:
Timing is set at 6 degrees BTDC, MSD Atomic EFI and the A/F ratio is set at 14.7,
Click to expand...

I'm puzzled by this... did you mean 16 degrees.? A/F ratio 14.7? is this at idle? Sounds a tad on the lean side. High 13', would help cool the engine also.
 
Unforgiven said:
I'm puzzled by this... did you mean 16 degrees.? A/F ratio 14.7? is this at idle? Sounds a tad on the lean side. High 13', would help cool the engine also.
Click to expand...

Nope. 6 degrees at 700 RPM. Any more than that it pings. I have the EFI set at 14.7 both at idle and WOT. This ain't a race truck. It's a K20 and a daily driver/hauler/tower. I'm thinking its time to readdress the timing curve.
 
Unforgiven said:
Do you have an electric water pump to circulate the coolant when engine is off? I only ask because you said you do a cool down before you shut off the engine. Without an electric pump, the fans would only cool the fluid in the radiator because of no circulation. I had a heat issue with my truck a few years ago, and discovered an air pocket above the thermostat. I made a bleeder to evacuate any trapped air in the system. This may not be your issue, but I thought I would mention it. If the steam holes are blocked, I can see that being an issue too.

Nice engine combo by the way!
Click to expand...

That's a good idea. remote water pump on a timer or t-stat. To the drawing board......
 
I would certainly try adding the water wetter, as a time delay may remove heat from the radiator,
but its coolant in the heads and block that are boiling,
adding the additive reduces the coolants tendency to boil as it more effectively absorbs heat
Water-Wetter.jpg

steampocketsf.jpg

tst4.png

ONCE COOLANT BOILS it lost the full ability to absorb heat as partial direct contact with the metal surface is partially lost, one reason cooling systems are pressurized is to increase the boiling point threshold
 
Don Norton said:
Nope. 6 degrees at 700 RPM. Any more than that it pings. I have the EFI set at 14.7 both at idle and WOT. This ain't a race truck. It's a K20 and a daily driver/hauler/tower. I'm thinking its time to readdress the timing curve.
Click to expand...

The only time you target AFR 14.7 is when you want a catalytic converter to work at its best, 14.7 is also the most knock sensitive AFR, and only used for light throttle, it would be a good idea to make a new AFR and timing curve, it would run cooler, stronger and more efficient.
 
Don Norton said:
That's a good idea. remote water pump on a timer or t-stat. To the drawing board......
Click to expand...

Well... a remote pump is an option.... but I was referring to replacing the mechanical pump with an electric pump. You can set it up to turn off and on with a thermo switch installed in the head. This would allow the coolant to keep circulating (even when engine is off) until it reaches
the shut off temps. Now be aware that an electric pump does not move as much coolant as a mechanical one. But it may not be enough to be concerned about.. I would read up on them and make a decision.

As far as the timing and A/F .....Stock cams idle around 4-6 BTDC ... perfomance cams like a little bit more initial..you can rework the dizzy to
limit the total timing. The 14.7 A/F at wide open is waaay to lean.. think about it for a second. You are dumping X amount of fuel in at idle,
with a given amount of air. Now if you introduce more air (at WOT) and keep the same amount of fuel mixed with that air...You go lean..Which equals HOT. More fuel is always safer to combat heat and knock.
Grumpy just made a thread on AFR'S ... it's a good read.
And YES... the water wetter does work. I use it in my truck.
 
Unforgiven said:
Well... a remote pump is an option.... but I was referring to replacing the mechanical pump with an electric pump. You can set it up to turn off and on with a thermo switch installed in the head. This would allow the coolant to keep circulating (even when engine is off) until it reaches
the shut off temps. Now be aware that an electric pump does not move as much coolant as a mechanical one. But it may not be enough to be concerned about.. I would read up on them and make a decision.

As far as the timing and A/F .....Stock cams idle around 4-6 BTDC ... perfomance cams like a little bit more initial..you can rework the dizzy to
limit the total timing. The 14.7 A/F at wide open is waaay to lean.. think about it for a second. You are dumping X amount of fuel in at idle,
with a given amount of air. Now if you introduce more air (at WOT) and keep the same amount of fuel mixed with that air...You go lean..Which equals HOT. More fuel is always safer to combat heat and knock.
Grumpy just made a thread on AFR'S ... it's a good read.
And YES... the water wetter does work. I use it in my truck.
Click to expand...


My bad. WOT is 12.7. Cruz is 14.7. I'm going to change the idle AFR to 13.5 this morning and add the water wetter. See what that does.
 
Grumpy said:
yes let us know how the changes work out
Click to expand...
Think that was the ticket. I set idle AFR to 13.7 and added the Red Line Water Wetter. Temps hold real good at 180 degrees and it does not boil after a hard run and shut down. Going to run it in this configuration and go do a long freeway cruz to see ho the temps hold a 75 MPH and after a shut down. Keep you posted. Thanks for the input.
 
Don Norton said:
Think that was the ticket. I set idle AFR to 13.7 and added the Red Line Water Wetter. Temps hold real good at 180 degrees and it does not boil after a hard run and shut down. Going to run it in this configuration and go do a long freeway cruz to see how the temps hold a 75 MPH and after a shut down. Keep you posted. Thanks for the input.
Click to expand...


Well, that didn't work. Still have to give it a cool down period. Operating temp's held very good at 180 degrees @ 75 mph. Notice a little pinging happening on up hill pulls. Think its time to replace the ole 45 year old dizzy and slow down the advance rate. The other thing I'm going to do is replace the head gaskets with the same Fel-Pro MLS 1144053 to keep the 10.5:1 compression ratio but this time drill the steamer holes on the bottom section of the gasket. The steamer holes are already there on the upper section of the head gasket.
 
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