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Why get hot over miles?!?!

Joined
Apr 29, 2001
Messages
2,141
Location
Rio Rancho, NM
Corvette
1981 HD Suspension; ZN1 Option
Hi folks,

Upon returning from Bud's Roast, Gail began to give me problems again. Getting hot after so many miles. It's been a problem i have been chasing for a while.

The usual scenario is me driving Gail cross country somewhere. She'll drive fine 4 or 6 hours, and then, the water temperature begins to creep up ever so slightly. From a solid 200 degrees F for the first four or six hours @ 80 MPH, and then climbs to 210, then 220, then 240 and so on. If I pull over and check her out, the overflow bottle is usually full. Sometimes with the auxiliary fan on in most extreme cases (240 Deg plus).

The backfiring does come back when this happens. I can't even driver her past 50 miles because the engine just gives out. She he has made me pull over more than a handful. In the early days of the problem, I thought it was the cap losing pressure, so I got an 18 psi cap. It only delays the problem.

So given the latest episode, I decided to pull out the radiator. It is now being gone over. The folks found a crack on the solder to the left tank, which seems to validate the long periods of driving problem-free. But I am not stopping there. I am replacing the water pump (the old "might as well" syndrome lol). I'm also contemplating pulling the intake and reseal the intake to the heads. I'm have not decided 100% to do this yet, but if the radiator folks tell me that it did not have major problems, I'm guessing that the motor is working too hard.

It it is hard to believe, it has been nine years since I put the engine back together, so I am checking it out in case the gaskets have deteriorated from sitting in the garage.

That is the other thing. She seems to break down from long periods of un-use. And that is my fault. Four weeks ago I drove her to work, but in my drive way i found out that her tires were at 15 psi. Yikes!!! :ugh:ugh:ugh

So keep 'em driving. They are like us. Breakdown from non usage. Lol
 
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That is the other thing. She seems to break down from long periods of un-use. And that is my fault. Four weeks ago I drove her to work, but in my drive way i found out that her tires were at 15 psi. Yikes!!! :ugh:ugh:ugh

So keep 'em driving. They are like us. Breakdown from non usage. Lol
I'm convinced that it cost just as much to drive a car as it does to leave it sitting around.:chuckle
 
Gerry, have you checked the t-stat as well....that helps to control the engine temp as well....if its weak it could contribute to your problem....
 
Gerry, have you checked the t-stat as well....that helps to control the engine temp as well....if its weak it could contribute to your problem....

Yes. It even now has a so called "fail-safe" t-stat. :(
 
Fan clutch slipping?

I replaced it last before pulling the radiator. In fact, I thought I had fixed the problem. Perhaps that is why it seems to run fine for four to six hours. And it ran slightly higher. :(

The radiator shop called me yesterday and suggested i buy a new core. And I was like,"but this core may have been purchased in the late 90's, but it does not have barely 7K miles!". It looks brand new inside. So I'm not sure if they are just trying to sell me a new core and being lazy about fixing mine.

I'm calling Dr. Rebuild this morning. :mad
 
Gerry,hows your air dams around the radiator????
I wonder if the upper dams are letting air over the top of
the radiator after a while.....
Just a thought....
 
Gerry,hows your air dams around the radiator????
I wonder if the upper dams are letting air over the top of
the radiator after a while.....
Just a thought....

Bill,

Do you mean the foam seals? There are remnants still there. But having the bigger radiator masked the problem, I suppose. Perhaps with a 3-row regular radiator it is indispensable, but with the four row radiator, never a problem before. But you are right. I plan to put new ones when the radiator returns to its place. :)
 
Yes! Gerry,the foam seals.... they help deflect the air from going over the radiator to going thru it...
which could be your problem,perhaps some of the air is going thru,
but eventually not enough,as it causes the radiator to over heat,the longer you drive it.
 
What kind of coolant do you use and how often had you changed it? Was the old one plugged at all?
 
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Yes, I'll install new ones, Bill. :thumb:thumb

Coincidentally, I just got a call from Dr. Rebuild. Doc himself researched it, and the ZN1 radiator nor replacement exists. He suggested I re-core.

I'm sure I can fit another radiator, but hanging on to originality, or at least the appearance of originality (such as in a core replacement), is important, otherwise, it will cease to be Corvette in the true sense, and becomes a resto-mod or close facsimile. lol

The radiator place is offering to re-core it with a core that has 20% more tubes (vertically, it fits more tubes in between the fins TIMES the circuits totals (4-core)). Again, not original. A bit of cheating perhaps. But how much is worth peace of mind on a long drive?

On the other hand, they can core it with the original number of tubes. And that has always worked. Just not cheap either way. :ugh:chuckle;)
 
What kind of coolant do you use and how often had you changed it? Was the old one plugged at all?

Usually Prestone. Changed four times since 2007, but refreshed a lot more lately with the problems I have described.

Here is a shot of what it looks like now inside.

20150425_191026467_iOS.jpg


second shot

20150425_191125276_iOS.jpg
 
Was not aware of that package on Corvettes. I knew about the gymkhana suspension but didn't know RPO ZN1 included the trailering chassis equipment, too. What all did that consist of (besides the hd radiator)?
 
Was not aware of that package on Corvettes. I knew about the gymkhana suspension but didn't know RPO ZN1 included the trailering chassis equipment, too. What all did that consist of (besides the hd radiator)?

Scott,

Back in those days some folks were adding hitches to their Vettes. My understanding is that the dealership installed the old hitches, not like the ones in todays trucks. (200 lbs tongue weight at most).

20150428_025443275_iOS.jpg


And here is how many had the option:

20150428_030129132_iOS.jpg
 
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I dropped off the radiator at another shop. This one is a 71 year old guy that specializes on old car radiators (like early 19 century cars). He showed me how my radiator core is fine. There is one small leak in one of the tubes near the left tank though, but he said that would not be a problem. :happyanim:
 
I dropped off the radiator at another shop. This one is a 71 year old guy that specializes on old car radiators (like early 19 century cars). He showed me how my radiator core is fine. There is one small leak in one of the tubes near the left tank though, but he said that would not be a problem. :happyanim:

This sounds much better. I couldn't figure out how a radiator would need much done after only 7K miles / 8 years. (unless it was dodgy to start with)
 
This sounds much better. I couldn't figure out how a radiator would need much done after only 7K miles / 8 years. (unless it was dodgy to start with)

Yes. I figure that the other shop was perhaps so busy that they did not want to bother. Their dad retired, so now the daughters are running the shop. I just wish they would have told me that they were too busy to bother with my radiator. I learned that they specialize in big radiators like for tractors and semi trucks. But then again, tried to stick it to me with a new core. SMH.
 
I think this explains alot:chuckle

Yeah, one daughter worked for the dad a good 15 years. She is the main tech. The other one is administrating, I think. But it was obvious a ploy to make their worthwhile and suckering me into a new core. I was like, well excuse me if I don't want to be your cash cow or golden goose. Lmao. :chuckle;LOL:L
 
Gerry,

I hate to even suggest it...but your symptoms sound a lot like a very slow leak between a cylinder and the cooling system. I've had this happen before...where the "leak" doesn't happen until the engine reaches a certain temperature. A cracked head can do this. The crack opens up at some temperature (around 205 deg when I had this problem) and allows combustion chamber pressure into the cooling system, which causes excessive pressure and pushes coolant out the radiator cap into the overflow tank...and out of the system ultimately.

Bill
 

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