chevymans 77

I've tried using one of the speedway TruCool aluminum radiators (universal fit) and it just will not do the job.

I have it sealed up to the core support and have 3 electric fans on it, a Mark VIII pulling and 2-12" fans on the front of the radiator pushing. I installed a rather large engine oil cooler, a stage III Stewart pump, a high flow stat from Stewart and have tried just about every timing setting I could but the temps don’t respond to any thing. I installed a radiator cap fitting on above the T-Stat so I could get all the air out of the system, the only issue with this is the pump will put up enough pressure to lift a 24lb cap ( when I blip the throttle) expelling a good bit of water to the overflow bottle. When I purchased the Stewart pump they told me not to install a cap at the T-Stat for this reason. I can only guess that the radiator flow capability is not sufficient and is causing this issue.

The temp stays around 180 while cruising around town or idling but once I get up to highway speeds it will very slowly start climbing, it will level out around 220* to 230* than once I slow down the temp will slowly come back down. The inlet temp and outlet temp of the radiator will equal each other while running down the highway so in my mind this indicates that the radiator is dissipating all the heat it can. I have removed the headlights and gave that a try to see if it may be air flow but the temps were the same.

I have verified the inlet temp and outlet temp of the radiator with an IR gun so I’m pretty sure these temps are correct.
I’ve read quite a few threads on cooling here and have decided to go with the Dewitt radiator along with the twin Spals.
I’ve looked into the BeCool radiators, the modular set-ups they offer, but it looks like the only difference is the fans, the radiator is the same in the kits. The only thing I had a question on was the insert that they install in the tubs for turbulent flow (not sure if this will make a difference).

One thing is for sure, I will test the capacity of the Dewitt radiator and fans once installed.

I’ll report back and let everyone know how it comes out, radiator and fans should ship in a day or so.

The cost for the BeCool set-up and the Dewitt set-up are just about the same so I went with Tom due to his support of the vette hobby.


Neal

TimAT

I'm interested to see what you find- I had the same thing with my 69 BB- when I took the front license plate and bracket off it was the end of my problems- just like you, above 70 MPH the temp would start climbing.

FWIW: I have the factory GM L-88 radiator along with an aluminum water pump. 69 had a little different scheme for the radiator- they had an expansion tank that is also the fill port with the heater hoses running thru it.

JoeC427

elle88

On my L88 engine I have a dewitts radiator ( new) with fan shroud , all seals , a 7 blade motor fan ( but I reduced the angle of the blades to take the fan to work like a 5 blade), 180deg Tstat.

when the car is at speed , the temp is pretty steady at 180 or so
the only time that temp rises to 190-195 is when I get back in town ( low speed) after driving hard the car out of town.

at the moment I'm keeping the licence plate in place. when temps will get higher in July-august i will possibly remove the licence plate and angle more the blades of the 7 blades fan

elle88

p.s. if you have a 77 vette, you can't remove the licence plate I think, but possibly you could fit a bigger chin spoiler, possibly the 78 pace car type.you should have more air flow.

roscobbc

On my 528 hp 489 I have used new DeWitt rad, sealed shroud thoroughly, have aftermarket water pump, stock viscous fan - repositioned license plate - now temps are 175/180 all day - although summer hasn't arrived here yet.

bashcraft

Could it be that 2 fans and an oil cooler in front of the rad is blocking a significant amount of air flow?

This sounds like a big issue. To me it indicates that the rad is not dissipating any heat. Little to no air flow?

I'm a believer of using the stock shroud and thermal 7 blade clutch fan. Thats what I use with a 502 and it never goes above 180*.

427Hotrod

My 540 is using a stock 427 radiator with a shroud and 7 blade fixed stainless blade. Stays cool just fine..even at highway speeds.

Are you still running without a hood? If so that will allow the air to go over the radiator and not through it.

Seldom does the *pusher and puller* deal work together. Puller are always better. If the temps are the same on inlet and outlet...you're right...it's doing all it can. It's not removing any more heat. Have you tried running with no t-stat? Have you verified the pump isn't a reverse rotation one for serpentine belts?

JIM

chevymans 77

I started with just the Mark III fan, than progressed to the 2 12" fans and then added the oil cooler. The temps had gotten better after adding the fans and oil cooler when at low speeds.

I would have put the stock fan and shroud back on but I'm running a serpentine set-up and can't fit it in there.

Neal

chevymans 77

I have the hood installed with cool air induction form the base of the windshield. I added the pushers after having trouble form the start also they are right on the oil cooler, thought this may help also.

I did try no T-stat a while back with no change. I installed a clear section of hose between the T-stat and the radiator so I could see if the pump was moving the water and to verify the flow, you would be suprised how much water those pumps will move. The pump will put up enough pressure that it would lift a 24lb cap at the T-stat.

Neal

gingerbreadman1977

maybe time to check that lower radiator hose. seems strange it runs perfect around town but not on the hiway. normally its the other way around when things go wrong.

billla

Good catch

If there's no temp drop across the radiator it almost has to be an airflow problem. It's not that the radiator is doing the best job it can - it's that there's not enough airflow to move the heat out. The fact that highway speeds are the issue leads me to believe that it's not the rad or fan - but just that there's too much stuff in the way to get flow through the radiator.

0Tom@Dewitt

Check that lower hose
Dump that filler neck on the thermostat
Start out the new package without the pusher fans

If you still have issues after the above changes and the new package is installed, I would go back to the standard water pump. By making this one change you'll be able to see if the high flow pump alone was helping or hurting. Dozens of people have told me they made their car run hotter because the flow was too much for the radiator.

L79racer

Change the water pump. You say that when you rev it up it puts out too much pressure. Well if its putting out that much pressure its probably flowing the water too fast threw the radiator at higher rpms and not letting the water cool.

chevymans 77

The lower hose is in two pieces, it has a brass insert were the two hoses connect along with the spring on the inside of the hose.

Neal

chevymans 77

Got the lower hose covered
I took the cap off the filler neck and made a solid cover for it.
I will install the new radiator and fans alone without the pusher fans.
If the temps don't come back inline I will install a regular pump and try that.

Neal

chevymans 77

Just to clerafy the pressure issue with the radiaor cap on the T-stat housing. I had two radiator caps, one on the T-stat housing and the normal one at the low pressure side of the radiator. The cap (24lb) at the T-stat would lift and the cap (16lb) on the radiator would not. This is why I said the radiator may be my issue, it may not be able to handle the flow that the Stewart pump will put up.

Neal

noonie

What is your rpm when it heats at cruise?

chevymans 77

around 2800 to 3000rpms.

Neal

jackson

When installed properly, I'm sure DeWitts will do a good job & that Tom's product & support is worthy of your business. That said, I doubt your TruCool rad itself is at fault.