I swapped out my leaking OEM radiator for a DeWitts yesterday. I have a 99' Vert, manual trans. Install of the radiator was pretty much by the book, fit of the new radiator was good. What is weird is that I'm seeing warmer than usual temps on the highway (201-205). This is higher than what I was seeing with the previous OEM radiator (199-201). I went through the usual "burping" scenario adding fluid as the engine warmed up, etc. With the increased coolant capacity of the new radiator over the old OEM, I am a bit perplexed as to why the temps are not lower. The radiator is sitting firmly in the bottom of the lower support, but seems to be about 1/2" higher than the OEM. The upper radiator support bolted down as normal, but the intake and bridge are raised a bit, pulling the air cleaner away from the back shroud by about 3/4" of an inch. This can't be normal I would assume. No, leaks, codes or anything else, just these "anomalies" I mention that have me perplexed. Any thoughts or suggestions welcome, thanks!

 

Did you reinstall the foam seals?

 

it might still have some air trapped somewhere, try running the car with the surge cap off and just let it idle for about 30mins making sure the fans cycle a few times and burp the hoses during the process... once that is done replace the cap and go for a drive and see how it does, then park it and when it cools you can remove the cap and add coolant if needed

 

 

it should sit the same height as before...something is not right....this also makes me think that you may not have the correct gap between the radiator and AC condenser

FWIW I added a SPAL kit when I did my Dewitts....money well spent if you are really concerned about temps...I had to with my S/C but thats another topic...

 

Upon inspection, there is a loose foam seal on the drivers side. This is the foam seal between the AC condenser and the shroud?

 

Will do.

 

and just to make sure, is the air dam still on the car?

 

Yes, it was not removed.I was able to clean the AC condenser without removing it.

 

Would it help if I elevated the front end (ramps)?

 

there should be a foam seal on both sides, they are cheesy but they do make a difference for the fans to work efficiently...I know mine got lost along the way due to all the mods I had done the SPAL fans overcame that issue, those suckers move some air


what temps are you hoping to achieve?

 

Low 190's on the freeway.

 

I just wanted to add that 205 is not bad, the LS1 is designed to run in those ranges....don't do what I did, in an effort to compensate for the heat soak of my maggie I obtained good temps during the Florida summer heat of 225 or less with the AC running in traffic with the car lowered right off the pavement.....sounds great right??? Come winter time the car never got hot enough to have heat

 

hmmm.....I did that by making my front plate filler a screen, cutting a hole in the bumper directly behind it which was necessary for what I had going on but overkill for your situation.

 

The radiator shouldn't have any trouble lowering the temps to the low 190's. It is double the cooling capacity of the OEM unit. If re-burping the radiator doesn't work, I'll have to go back in and take everything apart and then re-install it. Something doesn't seem right, and when I know it isn't right it bugs the crap out of me. I tried to do this right the first time, but I'm certainly no expert. That's why this forum and people like you make it worth while for do-it-yourselfers like me, I want to take a crack at it. Best of all, I have the time since I'm retired so I'll enjoy it anyway cause I'm working on my Vette to make it better.

 

What temp does your thermostat open at?

 

187

 

I have a 160 tstat, mine runs 185 on the highway in 90 plus heat stock radiator

 

So, 5 degrees hotter.
What was the outdoor (ambient) temperatures for these two tests?

I wouldn't tear it all apart, you won't accomplish anything. You might have air but I doubt that too.

It is normal to expect some form of lower temperatures with a radiator upgrade but that isn't always what happens and here are a some reasons why...

Ambient air. Engines are water cooled but air cools the water. If the ambient air changes so does the ability of the radiator. When your cooling system is maxed out it could be a 1:1 ratio or 10 degree hotter air means 10 degrees hotter engine. This also works in the opposite direction and its probably one of the reasons thermostat debates exist. A 180 stat does nothing with one car in 100 degree heat but the other car with the same stat in 70 degree air shows a big difference. Air temperature is a huge variable and people hate variables. We want "do this, get that " answers and with cooling and it just doesn't work that way.

Allow me one more analogy...let's say you like it cold in the house. You set the thermostat to 50 and the coldest it gets is 74. So you change out the system from a 2 ton to a 3 ton and now you can get to 65. But what if you set it to 74? It will run the same as the 2 ton did. Does that mean the bigger unit isn't better? No, it means something else is controlling the final temperature.

You could have crap in the condenser, limiting the air flow to the radiator. Your stat may not be functioning the way it should, both temperature setting and flow, and reprogramming the fans to come on earlier and stay on longer isn't a bad idea.

 

I agree about lowering the fan on/off temps but that only helps at idle, his concern was at cruise speeds when the fans are off... personally I think he could get the temps down a tad, I run one of your radiators as well and I also have a big 3" thick intercooler in front of my condenser/radiator and in the hot tx summers it will run low 190s all day long while cruising and typically doesn't get over 200 degrees unless I'm racing