66Laguna450hp

I just purchased a 66 laguna blue with bright blue interior. It's L72 car and I'm having problems with it overheating. Any suggestions or tips

Vetteman Jack

Moved to C1/C2 Corvettes.

Nowhere Man

Google corvette cooling 101 written by John Hinckly in Corvette enthusiast magazine

R66

Welcome to the forum. I am sure you will need to provide more details on the engine and cooling system to get good troubleshooting recommendations. Does it overheat idling, on the highway, etc. What is the definition of overheat - 220 degrees F ?? Is it puking fluid? Have you verified the temp with an IR gun? Fan type - stock or electric or ??? Radiator original or new or ???
Look in the FAQ section at the top of the first page and I think you will find the cooling 101 article, or at least a lot of information.
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CaptainEgg

Is the timing correct? Bad thermostat? Is fan mounted properly in relation to shroud? Is radiator good? Did this just start? Is it boiling over or just reading hot on gauge? Not really enough info to fix problem.

C2Scho

Or it could be that your temperature sensor unit screwed into your intake manifold is reading way high but your temperature is actually okay. Those units nowadays (even brand new in the box) are notoriously inaccurate. We need a lot more information from you before we can accurately begin to diagnose your problem and help you fix it. Welcome to the Forum. C.J.

Vet65te

And another 'Welcome to the Corvette Forum'. Your question comes up fairly often. Could be a number of things and you're already getting some good advice to help clear it up.
When the dust settles, have a look at this long running thread started by a fellow Forum member on "L72s". So far we've gotten over 50 owners to post up pics and tell us the background
story on their L72's. Some are bone stock, others, like mine, 'not so much' but some great reading on all of them. We even have input from folks overseas like Germany, France, Sweden, Switzerland and the UK.
Hope you joins us on this thread.
C2 1966 L72 count - CorvetteForum - Chevrolet Corvette Forum Discussion
Mike T - Prescott AZ

66Laguna450hp

it all stock. Had a frame off couple yrs ago. It will over heat sitting and driving. And yes does puke out. My first thing is adding electric fans, then flushing, thermostat, then water pump.

kellsdad

I suggest you don't start buying solutions until you have identified the problem. Root causes can be: 1) too much heat generated by the engine; 2) poor circulation of coolant; 3) poor heat transfer at the radiator; and 4) insufficient air flow through the radiator. I'd start by eliminating possible causes as a way of homing in on the root cause. For example, be sure the fan is operating correctly and air is not bypassing the radiator through openings around the shroud. When you know that is not the problem, check it off and move on to the next issue (e.g., engine producing too much heat due to bad tuning).

Uncle Pasko 73

The first thing to do is check your timing. If your timing is off you'll be chasing your tail trying to fix it with parts.

road pilot

Don't throw parts at your problem. The end result
the engine over heats , now diagnose the problem
and your problem will be solved. Has your rad hoses
collapsed? Yes or no. Then go to the thermostate good or bad?
move on....down the line of reasons for over heating. Radiator
stock?? You could need a new one.
Good luck

Factoid

This could be as simple as a stuck thermostat. My L72 never overheats, even when idling for long periods in 90 degree+ heat.

Electric fans are definitely not part of the solution!

Vet65te

To the Original Poster - it has to be frustrating to buy a Corvette that has been restored only to find there are issues with it. It's a Royal Pain to have to break out the tools to get to the bottom of this but
it's the only way. When you have the time, check a few things that have already been suggested and report back and hopefully in a short period of time, you'll be back to enjoying your new L72.
Mike T - Prescott AZ

leif.anderson93

A car could have a had a frame off restoration a couple of years ago and never been driven since. These cars need to be driven...often. Do you know if the radiator was replaced? I believe you have a coolant flow issue. Typically, if a car will overheat while driving, the radiator is not doing it's job of cooling or the thermostat is stuck not allowing the coolant to move through the system. Are you mechanically inclined? Do you plan on diagnosing this issue by yourself or by a respected mechanic who knows old cars?
As stated, this conversation comes up often in the summer months and there are scads of threads to search...but the best article is John Hinckley "Cooling 101" (RIP)

Lotsacubes

Agree with all about throwing parts at it. After I made sure all the basics on my L72 were correct, I replaced the original radiator with a HD Dewitts. Now can idle in 90+ southern summer days. Before stop lights made me nervous. Not now.

lawdawg

Hey Laguna,

Slow down a bit and lets eliminate the most probable mechanical issue first. The absolute first thing to check is the heat riser located on the passenger exhaust just between the cast manifold and the pipe itself. it is spring loaded and you will be required to wire it open with some stainless wire or a stainless exhaust wrap. you should be able to move the weight on the exhaust riser 90 degrees with your hand before starting the car. if the riser is stuck, it will overheat every single time and you will have much larger issues pretty quickly until you fix that.

Personally, i take them off and remove the butterfly inside the riser with a plasma cutter so that it appears stock from the outside, but the flap is gone inside.

when you determine that this is functioning correctly lets see a picture of the inside of the radiator thru the cap hole - running and not running

kkupec02

welcome

Duck916

Welcome aboard!

Lots of good suggestions here. I still would want to verify you really have a problem. Is the coolant level correct in the radiator to start with? If it's overfilled, it will burp out some coolant when it gets hot. I'd definitely verify the actual temp with a quality infrared temp gun.

Once it's confirmed you have a true overheat condition, my checklist would be:

Proper fan
Fan about halfway in the shroud
Correct timing
Radiator hoses not collapsing
Proper heat riser function (or eliminated)
Seal off air leaks between radiator and shroud

Dad's '66 427

Could someone please post photos of the seals around the radiator, shroud and hood that have been mentioned, that should be on the OP's car?

Thank you.....

larebob

Our L76 '65 had an older radiator with a Harrison sticker, but, while it fit very well, was not looking like a first class unit. It also had a visible repair to one tube. The clutch fan looked new (we've had the car some 2 years and it was an old, rather complete, restoration). Just threw the suspect parts at it - new DeWitt's, new fancy recommended clutch fan (165 degree cut in) and...... Bob's your uncle, now under the gauge center on 85 degree days at constant 75 mph (3:70 rear end). Previously it would pass the center of the gauge after 9 or 10 miles at 70 mph.