602 Overheating

[CC57]

Requesting suggestions on how to cool down #05 racetruck. It has been running consistently hot: 220 to 230 to 240 degrees.

 

Couple of races ago the temp went to … well I don’ know, it buried the needle. But for only a lap and a half (turned out the fan fuse popped).

 

Made some changes race before last, still ran hot.

 

Made big changes (read expensive and see details below) before last night’s race: they didn’t help: I pulled off when the temp hit 240.

 

During cautions, I bump it up to Drive (T-350) and it will cool down to about 190 to 200. But once we go Green, doesn’t take long to heat back up – excessively.

 

I don’t think it’s a faulty gauge because I’ve seen it “look like a steam locomotive as the water comes out of the overflow vent.

 

Here’s what I have:

The nose has many openings in it.

 

.040 aluminum “air box” between the nose piece and the radiator forces 95%+ of the air through the radiator (distilled water, 27# cap, 1 bottle of water wetter and 1 of purple ice (only purple ice for sale at the track).

 

When I fill the radiator with water, I usually pull the cap off, run it up to around 1,500 or so, top off the radiator, and put the cap back on.

 

Replaced the triple-pass radiator with a brand new double-pass.

 

16” electric puller fan, mounted on a very nice Jeg’s shroud (putting in a plug for Jeg’s because I was impressed with their shroud) on the back of the radiator. 99% of the air passing through the radiator is pulled through the fan. Tested to see how much suction the fan was providing: placed a towel on the front of the radiator and the fan “sucked” it tight to the radiator.

 

No restrictor in the “thermostat hosing” of the water neck on the intake manifold. And after talking to Stewart engineers, I don’t plan to put one there.

 

I started with a v-belt 15% gear reduction pulleys. I just replaced it with a serpentine ~5% reduction system. I went to the serpentine in the hopes of reducing if not eliminate possibility of belt slippage, plus I had to make room for the upper radiator hose to clear the alternator when I changed from triple-pass to double-pass radiator.

 

Replaced water pump with Stewart Stage-II I had been running on my Mod

 

Upper hose is 2-race old Gates hose with the spring vulcanized in the rubber. Lower hose is a Gates green strip with internal spring (it’s in good shape)

 

The 4412 had 77 jets, but when I looked at the plugs, looked like the truck was running a bit rich. I changed the jets to 75 (local carburetor expert agreed and supported the change)

 

Changed timing from 38 to 32. (big swing, but getting desperate)

 

Think that covers it.

 

Any suggestions?

 

Anything I should maybe be looking at in the engine itself.

 

And thanks for any comments and suggestions. If not only for me, but whoever else this thread may help

[jwmbishop]

Has it EVER ran under 225? If the popped fuse was the first overheat and now you can't keep it cool - you may have cracked something or broke the flame ring of the head gasket.

 

Do a CO check on the coolant - Combustion pressures (and temp) can go into the water with no leakage in a leakdown test. Checking the Carbon Monoxide in the water will tell you if you've already damaged the flame ring or cracked something.

 

The Stewart pump makes it's own head pressure (therefore no nucleate boiling - aka cavitation - at the impeller center) regardless of water neck restriction so I agree with you on not going that route.

 

As you see it cooling down in D (lower RPM and less airflow from fan - even though YES there is less therms being made from no hard throttle) it's obvious that your radiator is doing it's job - try reducing the pump speed. You went from -.15 to -.05 so try -.25 - this may give you a heat problem under yellow - but burping and revving would control it. To see if this would work before making the changes just run it hard during practice - get the temp up and go into D - run as hard as D will let you. If it goes down even under hard throttle loads in D you would very likely see a drop by slowing the water!

 

Also may want to tap the rear of the intake at the water and bring it out to the water neck.

 

Is your Trans loading the water temp or do you have an isolated trans cooler? If you are pumping the trans thru the radiator try putting the cooler between the trans out and radiator in so that it can take some heat out of the fluid before it passes thru the radiator.

 

Inside the engine - tight rings, tight bearing clearances will contribute to friction and heat. Large overbore will thin the walls and thus transfer more heat to the water (I built a .060 455 closed jacket boat engine that we NEVER could get under 220 and usually saw 245 - on sonic test we found a VERY thin wall, sleeved it and she never went over 200 again). A kinked or bent exhaust header will heat the heads and thus the water - especially if the one of the center two tubes.

 

If you have done any drain back work in the oil collection (heads and valleys) the oil my be running too fast leaving more work for the water cooling - but that typically does not present until your RPM range is VASTLY wide (like 3k to 11K).

 

edit - if the nose openings are too high you will be pulling the hot exhaust from the car in front thru the radiator. If you think this is irrelevant - we once chased a "setup" problem of blistering the right rear for three weeks - only to discover our exhaust turn out was cooking the tire!

[PAPA]

Sounds like you need a bigger trans cooler. At least check to see if the trans cooler is getting enough air flow to keep the fluid cool. Sounds to me the rad is doing all the work and that heats up the coolant.jmo.

[Truck99]

Guys, most of these trucks if not all of them have separate and isolated trans coolers. I believe his truck is the same way. We also can't do some of the internal engine mods that most would do because that is not allowed (crate motors.)

 

Robert, if you ask 10 truck guys if they have overheating issues to the 230-240 level, I'd bet at least 9 of them will tell you they do. Call me crazy, but I wouldn't pull off at 240 unless you have steam coming out of the overflow. Our gauge is currently not working right, so I can't tell you how hot ours gets, but it does get pretty warm. It doesn't puke water and the idiot light doesn't come on, but you can just tell it's up there pretty good. New gauge is in the works. We run the serpentine belts also. My opinion - they slip as much or more than good v-belts.

 

The good news is that the 602 seems to handle heat really well.

 

Call me crazy, but if it cools down to 200-220 or so during cautions and doesn't get more than 240 on your gauge, I'd run it as long as it's not looking like a steam locomotive.

[PAPA]

Chase

I understand what your saying but isnt a 50 degree difference between race condition and caution condition a little high?

 

I love these kind of questions. Im not a racer or crew chief but its like helping out without being there. Even though Im 60 years old I love to learn about these type of things. Sometimes I even get lucky and come up with the right answer........sometimes .

[abrungot]

How much space is there between the back of the hood and Windshield?

I ask because if there is not enough Air Flow out of the engine Compartment it will create Pressure that will slow the flow thru the Radiator.

Is the Electric fan mounted to the Radiator or is there a shroud so it pulls from the entire fin surface.

[PAPA]

Robert

Are you running a Trans Cooler along with your rad? Something else you might check just to make sure is the fluid line going to the rad. I had a cooler on a street car and replaced the metal lines with rubber lines.....BAD move. When a rubber line makes a bend or turn the I.D. gets smaller. thats most likely not your problem but you might want to check it while your going through all this.

[CC57]

First of all, thanks for all the input. Hopefully we’ll find out what - if any – problem I have.

 

Let’s see now…

 

“Has it EVER ran under 225?” Don’t believe so. This is a “new” – to me at least – truck. My 1st race in it was Speedfest. And if I recall, it was running hot (>230) then, but I was having too much fun and kept going. Said the heck with it, I’ll melt her down if I have to (yes, I would have regretted it if it did.) And speaking to the previous owner, they said they had issue with the truck running hot.

 

“Is your Trans loading the water temp or do you have an isolated trans cooler?” Isolated cooler, so this should be a non-issue.

 

I may have to try the “push it hard in Drive” test and see what happens. That’s a good “inexpensive” test.

 

“Do a CO check on the coolant” How and/or where would I go about having that test conducted?

 

“A kinked or bent exhaust header will heat the heads and thus the water - especially if the one of the center two tubes.” If all else fails, that may be a contributor. A couple of the headers tubes are “flattened”, but I didn’t consider them excessively so.

 

“..the nose openings are too high you will be pulling the hot exhaust from the car in front thru the radiator.” This I have to think about. I already have boxed in 95%+ of the area between the nose and the radiator (top, bottom and sides). Don’t know that I want to tape off/close any of the opening I have available to allow more air to the radiator.

 

“I wouldn't pull off at 240 unless you have steam coming out of the overflow”. Chase, up until last race, I was running a line straight from the overflow to the righty side of the windshield so I could look for steam/spray. And I’ve seen plenty the last 2 or 3 races. I was so confident I had fixed the problem prior to last weekend, I put the overflow canister back in line. So I didn’t see any steam. But when I opened the petcock on the canister, water came pouring out.

 

“How much space is there between the back of the hood and Windshield?” 1.5 to 2”

 

Fan is mounted on a shroud.

 

Plan to pressure test it this week. See if there’s a blown/leaking head gasket or something. If so, while I have the intake off, I’ll probably “tap the rear of the intake” at that time. Or, if the pressure test passes, I still may pull the intake and do that.

 

Thanks very much all and keep the suggestions coming.

 

The truck - and the driver - is starting to come around. Now if I can just keep her on the track.

[poorboy]

Put a 28-32 lb radiator cap on it and that will raise the boiling point some more, may not steam then.

[4cylfordz]

how large is the oil pan on the engine, often if it's a small pan the oil is probably overheating as it averages around 10-15% more than the water temperature. an oil cooler is usually good for almost 20 degrees of water temp If you get a good sized one, though remember to install it behind the radiator as it will overheat you if put in front.

[jwmbishop]

Block Check - I have found these immensely valuable in the past!

 

I can recall nights pulling off after the main at 245 with a 28 lb cap and no problems. Heat is power and power is heat.

 

Catch can should have water in it. It is not just to catch water from an overheat it will allow it to pull back in as it cools. From 100 to 240 the water volume actually increases (thermal expansion)! A gallon at 240 becomes .95 gallons at 100. Your catch is there to accommodate this and not have you loosing any.

 

good call 4cyl - I forgot all about increasing the volume of oil to catch more heat!

[JamesHigdon]

We have had issues like this before and while I'm not really an "expert" I can try and help. We built an '86 Camaro that from the moment it got a new motor in until it left here always got hot (235-240) during highway driving. As it turned out the company that put the motor together installed the wrong intake manifold gaskets thereby restricting the water flow enough to cause over heating. We tried a high volume pump, drilled thermostat, a hugh 3-core radiator and electric fans that caused a low pressure area in front of the car you could see on radar. Nothing worked. I have also seen a camshaft installed too advanced, a water pump with a lose impeller, a water pump with a poorly installed impeller, new radiator hoses coming apart on the inside, manufacturing junk in a new radiator, rust scale in an older engine block, the wrong head gaskets and a tight motor causing high oil temperatures all cause over heating...anything sound possible?

[jwmbishop]

I started with a v-belt 15% gear reduction pulleys. I just replaced it with a serpentine ~5% reduction system. I went to the serpentine in the hopes of reducing if not eliminate possibility of belt slippage, plus I had to make room for the upper radiator hose to clear the alternator when I changed from triple-pass to double-pass radiator.

 

Replaced water pump with Stewart Stage-II I had been running on my Mod

Just had a thought pop into my head. The GM serpentine is a reverse rotation (counter clockwise) water pump - the v belt is not. Same pump on both installs?

[Truck99]

I started with a v-belt 15% gear reduction pulleys. I just replaced it with a serpentine ~5% reduction system. I went to the serpentine in the hopes of reducing if not eliminate possibility of belt slippage, plus I had to make room for the upper radiator hose to clear the alternator when I changed from triple-pass to double-pass radiator.

 

Replaced water pump with Stewart Stage-II I had been running on my Mod

Just had a thought pop into my head. The GM serpentine is a reverse rotation (counter clockwise) water pump - the v belt is not. Same pump on both installs?

 

I think he's talking about aftermarket serpentine pulleys and belts that bolt on to the conventional water pump rotation.

[CC57]

Chase is correct.

 

I replaced the v-belt pulleys with serpetine and cog drive pulleys; utlizing the same Stwart pump, power steering pump, and alternator.

 

On the oil cooler. I've already been strongly considering installing a remote oil filter. Probably going to go ahead, bite the bullet, and add a cooler while I'm at it. Like I told someone the other day, I have a monthly racing budget. I believe I am now spending December's budget ...

 

Also, in the next day or two, will be pressure testing the system. And, depending on the outcome, may performthe CO test too.

 

Thanks again all.

 

It's so frustrating to be making some progress while on the track, but not being able to finish the job ....

[CC57]

how large is the oil pan on the engine, often if it's a small pan the oil is probably overheating as it averages around 10-15% more than the water temperature. an oil cooler is usually good for almost 20 degrees of water temp If you get a good sized one, though remember to install it behind the radiator as it will overheat you if put in front.

 

7 quart.

 

And if (when?) i install the cooler, it will be mounted somewhere behind the cab, with it's own fan mounted on it.

 

Thanks 4cly

[HiTech]

WE FOUND MANY YEARS AGO ..THE TIMEING CHAIN OFF ONE TOOTH ..MOTOR RAN GREAT .BUT AT HIGH SPEED RAN HOTTER THAN HELL ...SORTA WHATS GOING ON HERE .A FEW YEARS LATER MY MOMS CADDY WOULD DO THE SAME THING /7 TIMES IT WENT TO BALEYS ..THEY TRIED EVERYTHING TO COOL THAT MOTOR DOWN WHILE TRAVELING FINE ON SLOW DRIVEING ..EXCEPT CHECKING THE TIMEING CHAIN IN WHICH I BROUGHT UP MANY TIMES .WELL MOM MELTED THAT MOTOR ..THEY CADDY DID NOT WANT TO COVER IT ..14000 MILES THEN ...I MADE A BET WITH THE BIG GUYS .IF IM WRONG I PAY .IF IM RIGHT THEY PAY .. I WAS RIGHT.... OFF ONE TOOTH .....NOT SAYING THIS IS THE PROBLEM ...BUT HEY WHY NOT TAKE A LOOK ..FUNNY THINGS CAN HAPPEN ..

[SASPEEDRACER24]

Just curious and a shot in the dark but do you run an alternator with all of those electronics on the car? How old is the battery? If you have a signifigant enough drop in voltage with all of those fans ect. they may shut down or slow and become inconsistant. May also check the wiring to the fan either for a loose connection or intermittent connection like a bad or going bad switch or relay...

[jwmbishop]

will be pressure testing the system. And, depending on the outcome, may perform the CO test too.

When a history of numerous overheats is present I always CO first - you can have a minute leak so small water can't pass - but CO gas (and it's heat) does. I have passed PT and cleared for track only to finish blowing a head gasket later without even truly overheating again (yea it went off the needle once the gasket blew but was at 195 prior).

[jwmbishop]

Another duh moment. Never asaked where you are sampling temp at. You can be at 200 in the cylinder head between the intakes - and that's perfect. But there is a lot of heat goes into the water after that point - from the exhaust area jacket - and you could see 240 out of the water neck and as long as water isn't leaving the system there is no real issue.

 

We had one that we were sampling in the block and it would run 200 all nite as soon as he shut it off it would peg the gauge at over 250. That was that extra heat coming back once the pump stopped pumping. So we sampled the outlet as well and saw it at 245 while the head was 200! Thats the main reason an 18 lb cap just won't cut it in racing - it lets the water leave too easy!

[Boernebullet]

The G.M. 602 Crate Engine requires a "1" inch water restrictor in the thermostat housing to prevent overheating

 

Greg Spreen

[CC57]

The G.M. 602 Crate Engine requires a "1" inch water restrictor in the thermostat housing to prevent overheating

 

Greg Spreen

Greg, check your PMs please

[1-Crew]

The Stewart pump makes it's own head pressure (therefore no nucleate boiling - aka cavitation - at the impeller center) regardless of water neck restriction so I agree with you on not going that route.

 

That doesn't make sense to me.. Restriction at the thermostat housing creates pressure in the block, preventing nucleate boiling at the hot spots in the head. Nucleate boiling and cavitation are different processes. The cavitation event may start as nucleate boiling from the surface of the impeller blades due to the reduced pressure on the back of the impeller blades but it can also be caused by external introduction of air or steam. The Stewart pump may have a restricted outlet that lets it build pressure in the pump itself but that does nothing to control nucleate boiling in the rest of the motor. The pressure inside the pump would help control cavitation until an external source of air (or steam) interrupts the process. At high flow rates and temperatures you might be able to create and sustain enough fine bubbles to effectively be circulating foam, not liquid. Once that happens, cavitation at the pump is inevitable with subsequent loss of coolant flow.

 

"Nucleate boiling is characterized by the growth of bubbles on a heated surface, which rise from discrete points on a surface, whose temperature is only slightly above the liquid’s. In general, the number of nucleation sites are increased by an increasing surface temperature.

 

An irregular surface of the boiling vessel (i.e. increased surface roughness) can create additional nucleation sites, while an exceptionally smooth surface, such as plastic, lends itself to superheating. Under these conditions, a heated liquid may show boiling delay and the temperature may go somewhat above the boiling point without boiling." http://wapedia.mobi/en/Boiling

[Truck99]

The G.M. 602 Crate Engine requires a "1" inch water restrictor in the thermostat housing to prevent overheating

 

Greg Spreen

 

Greg, can you elaborate when you have a spare minute? We've always run wide open in the water neck and never had an issue, but this 602 has been a bear to keep cool at times. Stewart pumps does recommend no restriction in the water neck and 1:1 pulleys, so I'm wondering what you are on to here.

 

Thanks for sharing the info.

[CC57]

Greg, I too would like to know.

 

On a related note, this engine has run hot both with and without a restrictor.