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Cadillac 500 temperature problem

C

Capt Ken

Member
I have rebuilt my cadd. 500 engine. Added 2:1 Belt drive and 3-Blade Power shift props. Engine wants to run hot over 3000 rpm. Under 3000 no problems. Changed water pumps, new radiator the list goes on. I think the 2:1 belt drive is the problem. Does anybody have a 1.5:1 drive. My drive does not have 50 hours it. Any suggestion? :oops:
 
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All new parts. Work done by an engine shop in St. Pete. I took the engine back and they can't find anything wrong. I have checked timing, changed distributor nothing seems to help. My radiator is aluminum. My current thought is a bigger radiator. The belt drive was a mistake for the caddy. I would have to rebuild the engine mounts, cage etc to go back to direct drive. Really interested in a 1.5 or 1.7 : 1 drive. Thanks
 
what temp thermostat are you running? Make sure there is no air in the system. I took my thermostat and cut out the thermostatic element and turned it into a flow restrictor. I know I don't run the rpms you do but my engine never gets above 165. I know a guy running a 2:1 belt on a 549 caddy with no trouble
 
are you running a thermostat and what temparure is it . cadillac engines have a bypass built into the block .the thermostat controls this bypass when it opens it has a round disk the risticts the passage. currently there is the stock 190 degree and someplaces you can get a 180 ordered in
by not running a thermo the water will just be recirculated through the pump and motor however some water will go through the radiator and cool the engine. I know of some direct drives that run with out thermo,s , reductions will usually run hot. I don't recomend this but i have blocked the bypass hole on one or two cads and replaced the cadillac thermo with a lower degree standard no restrictor disc thermo, and that works but you have to look out for high block water pressure . I drill small holes in the thermo to bleed off water pressure. or run no thermo at all wich may be alright . my old caddy is running a 2:1 belt with the bypass blocked with a 160 termostat at cruise or wot it runs about 175 wich is just fine for me. hope i haven,t confused you to much
 
Stan is rite . Buy a real stat drill hole , just water no additives no green stuff . its not staying in rad long enought . too much flow ! Volume pump not always a good idea! The green stuff dont displace heat at all dont know why they call it coolant !
 
Hi Ken,

This is very important. I had a simular problem. It could be that your belt drive is installed improperly. To make a short story long, where the belt drive attaches to your flex plate / crank shaft, you could be causing your crank to push real hard on your engines thrush bearing. You have to make sure the lower belt drive pully shaft is properly secured to the bell housing bearing and not pushing your crank shaft either forward or reverse. Your crank has to ride neutral in your engine block. An improperly installed belt drive will always cause engine overheating and wallet drain.
 
hey ken, one bad problems with a caddy is trapped air in the water system. if all the air is not out it can reach high temps really fast.
if your thermostat does not have a weep hole in it you need to drill one.
normal caddy temp should be 190 to 210 anything less might make not run
to its potentail. do not worry about the temp if it is in these perameters.
when you get above 220 and continue to rise you know something is wrong. caddy motors love running in this range because of there high
nickel content of the motor.and that is also why they are light for a big block.just curious how did you fill the motor with water.
 
Guys I thank every one of you for your help. Keep it up. Maybe we can solve this. Anyway, I have tried 185 and 190 thermostats. I have run the boat with the thermostat as a restrictor only. I carry all three on the boat. I pulled a vacume on the cooling system and removed all the entrapped air. Tried "ice water" with no difference. Currently running tap water with no additive. As far as the alignment of the drive. My first response would be there is no problem. I will look at it some more. There is abosolutely no heat on any bearing. I am interested in the comments about the bypass. Need more information on this. I feel that a larger radiator will help. Again. Thanks to all!!!
 
Yeah Ken,
As far as the belt drive alignment, if you loosen the allen screw that clamps the lower pully shaft to its bearing where it protrudes from the lower part of the bell housing and then remove the 4 3/8" bolt connecting the bearing to the bell housing, the bearing should slide easly over the shaft. There are more detailed directions at http://www.airboatdrives.com/install.htm. I only mention this because reading your postings about overheating reminded me of what I went through. By the time I figured out what was wrong, I had to have my block / crank remachined due to the wear. In my particular case my shaft was rusted to my bearing clamp on the belt drive.
 
ken what type of radiator are you running,is your temp guage electric or thermocouple.and what temps were you hitting anyways?
 
Aluminum GM radiator. Below 3000 rpms temperature is less than 190. The 3-Blade Power Shit prop is set at 12degree pitch. Boat performance is ok. Not great, but runable. At 3100 to 3200 rpms the boat performance is great. Water temperature climbs. I don't let it get over 225. I have changed gauge and termocoulple. My boat wants the props turning at 1550 to 1600 rpms. With a 1.7 or 1.5 : 1 ratio I could get the engine rpms under 3000 and still have good prop speed. I have played with the pitch, but little if any temp. change. I have seen much larger radiators on similary airboats. That would be an easy fix. Thanks for the advise.
 
You might try running distilled water. It transfers the heat better than antifreeze mixes. You will need water wetter and some type of anti corrosion additive too.

Jim
 
my other only suggestion ken would be to buy an aftermarket cooling
electric fan they are less than a hundred bucks easy to install just hook it up with a toggle switch and turn it on when you need it.
 
and i forgot to say take it back if it does not work. and i also wanted to say your radiator should be atleast a large 3 core or smaller 4 core.
 
capt ken as far as the bypass goes when you remove the thermo look down under were the thermo was and you will see a round hole in the block this is were the water goes back to the water pump. on cadillac thermostats you will notice a round brass disc attached to a shaft as the thermo is heated by the water the spring pushes the disc down thus restricting the bypass . you must run a cadillac thermo. as far as radiators go i run a big block afco from classic airboats a dedenbear filler to git water in the motor timing set right and like the other posts mentioned you have got to bleed the air . if you ever get a hold of a motor were the bypass has been blocked off, do not use a cadillac thermo in it, will never open
 
run it, put water in it,run it, put water in it .do this about maybe fifty times, maybe not fifty times but it sure takes alot. put bleed holes in thermo if you run one.
 
Capt. Ken,

Have you magnafluxed your heads? Several guides I run with use Cadis - all are direct drive. They have regular problems with cracked heads / blown head gaskets until they drill and roll pin the head gaskets between the head bolts at the head's corners.

I have always been told Cadis make peak torque / hp at 3K and essentially are done at 4k. Are you trying to twist SBC revs out of this Cadi? Sounds like you might be experiencing some internal torque bind above 3K.

Good luck. There are terrific Cadi xperts on this site. BigBoom and others.
 
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