High coolant temp

[secondchance]

I replaced my radiator (OEM) about 5 years ago and installed Marc's chip about a year ago and she had been running at around 213 - 215.
Last week in 90 degree weather in rush hour traffic I noticed temp gauge hitting 230. So, I turned off the AC and temp came down to 213 and as I drove home.
Yesterday (90 degree day), driving back from the body shop (yes, I got her back and she looks perfect!), driving 65 mph, temp was a 225. Normally, 65 in 6th gear use to be around 213 and a little cooler in 5th (better coolant flow I figured).
I will check for any debris on the front of the radiator and fans (been busy).
Anyone had a similar experience?

[HIZNHRZ]

Yun, with time and mileage (depnding on driving conditions) the conditions you are describing are what I experienced with my Red/Gray 91 fair weather daily driver. At the time the car was about 10 years old and had ~15K (very short commute to work) miles. I pulled the radiator and cleaned it and the car again ran cool again. If you saw what I cleaned out of the radiator fins you would have thought I drove the car at the beach. It was a very fine sand like material. It was almost more like dust than sand but the radiator was packed with it; especially towards the bottom. After cleaning it out, it was only about another year before the running unusaully hot conditions returned.

I pull the radiator again. Mileage was only another ~8K miles but the radiator was as loaded with sand/dust like material again that was very hard to see when crawling under the car or when looking from the top. This time I replaced the radiator with a Fluidyne radiator and thermostat. The car ran cooler than it ever had. It's only a guess but I'm thinking the stuff that loads up the radiator has something to do with the crap thrown on the streets in the winter.

I sold the car soon after. I do talk to the new owner. The car now has over 30K miles and the new owner has never brought up and cooling issues. The only other thing I can say is the stuff was very hard to clean out. I'm thinking as the open area aperture becomes restricted and it not only impedes air flow and cooling but it also loads back up again much quicker. I don't think it's your problem but I also have a 160 degree thermostate you are welcome to if you wanted to try it.

[secondchance]

Hate to admit it but I think you are right.
I drove this car after snow and all that stuff they sprinkled on the road.
I just checked Fluidyne but seems they no longer have one for corvette. Is fluidyne the wider one (racing application)? I hear Dewitt no longer offer one for C4.
Any recommendations - a good direct fit aluminum for street application?

thanks for the offer Scott. If I decide to try 160, I will call.

[pantera1683]

Hate to admit it but I think you are right.
I drove this car after snow and all that stuff they sprinkled on the road.
I just checked Fluidyne but seems they no longer have one for corvette. Is fluidyne the wider one (racing application)? I hear Dewitt no longer offer one for C4.
Any recommendations - a good direct fit aluminum for street application?

thanks for the offer Scott. If I decide to try 160, I will call.

There are plenty of replacement rads on ebay (china?), corvetterecycling (NOS great price), dewitts (they still make c4 rads), and others.

[Aurora40]

FYI, if it was while cruising in 6th, try downshifting to 5th. If that brings the temp down quickly, it is caused by the low coolant flow at low RPM. It's a common issue that doesn't really have a solution (other than to downshift or drive faster).

[secondchance]

FYI, if it was while cruising in 6th, try downshifting to 5th. If that brings the temp down quickly, it is caused by the low coolant flow at low RPM. It's a common issue that doesn't really have a solution (other than to downshift or drive faster).

I know. She was running 220 in 5th. Normally, in 6th would run 213 and 207 or so in 5th.

[secondchance]

Those who are using Dewitt - are they better cooling relative to OEM? I remember reading fans have a bit of difficulty pushing air through - true?

[GOLDCYLON]

Those who are using Dewitt - are they better cooling relative to OEM? I remember reading fans have a bit of difficulty pushing air through - true?

True thicker rad core


mine always runs cooler in 6th with a stock rad

[secondchance]

Mystery solved!
Rather than speculating I went for a test drive, noted it was doing the same thing - temp climbing even while cruising at 55 - 60.
Came back home, got on my back with a flashlight. It turns out that a plastic flap that is hung at the top of the radiator has to come down, tuck over the bottom of the front bumper and this is held in place w/ a plastic tab. It seems this piece has come loose and at speed this piece is piece is pushed back to the radiator. With both fans running, this piece get sucked towards the radiator further worsening the problem.
Hah! I don't have to spend a whole day wrestling with a radiator!:dancing

[GOLDCYLON]

You talking about the rain shield?

[secondchance]

You talking about the rain shield?

I don't know what it's called. It's a plastic apron attached to front top of radiator and comes down to and tucks under inside bottom of the front bumper. It sort of directs incoming air to the radiator.

[Kb7tif]

Has anybody tried to restict the flow in the coolant bypass line? Without blowing out the rad (ha). I read writings from people who had MH do this as a last resort type of thing that fixed high temps once and for all.:dancing
Saw pics of somwone who actult put in a shut off valve so he could set it for best results, Traffic, high revs ect.

[ittlfly]

Has anybody tried to restict the flow in the coolant bypass line? Without blowing out the rad (ha). I read writings from people who had MH do this as a last resort type of thing that fixed high temps once and for all.:dancing
Saw pics of somwone who actult put in a shut off valve so he could set it for best results, Traffic, high revs ect.

Yes! That was one of the main problems with my 94, overheating. I sent it to Mark (for that and other work). He did his normal radiator service ......then put a washer type affair in the by pass line at the T- housing. Instant fix. The car runs in the low 190's.....down from 220/230 before the ''fix''.

[secondchance]

No. That's not the one.
The apron I am talking about separates radiator intake area from the inside of the front bumper.
Next time I get the car on the lift I will take a pic.

[FULLPWR]

Well.......if you see this "apron" next time you are taking pictures, take a picture of this also so I can see how it fits :mrgreen:

http://i287.photobucket.com/albums/ll142/dynomite007/ZR1/Shroud-1.jpg

hey, when I changed my kn filter last week, I found the same one in your pic, but the radius part at the top was facing down to the very nose of the filter housing and the slotted part was coving a 1/4 of the top of filter housing, I thought as if to prevent water splashing into the filter. I put it back the same way, I didnt drive it today but will take pic of it tonite. hell now... I'm not sure if it is placed correctly or not. :confused:

Luis

[secondchance]

This may be the same piece. It's just that "perspective" of the picture amy be making it difficult for me to identify. Post a pic and perhaps I can make a better sense of it.

I drove the Z into work and temp is holding good. Never went over 208. Cruising temp was 201 in 5th.

Driving back home will be the true test since it will be around 90. It was 78 this morning.

[ittlfly]

Is this the apron you are talking about?



When you say Mark, do you mean Marc Haibeck?........ Thermostat modificatons are discussed here ;)
http://forums.*************.com/c4-zr-1-discussion/259664-thermostat-cooling-discussion-pic-included.html
http://i287.photobucket.com/albums/ll142/dynomite007/ZR1/A-THERM1-1.jpg

I'm not able to follow the discussion as I can't open the link as presented. However, this appears to be a picture of a thermostat. Mark Haibeck installed something what he refered to as ''a washer looking item'' to restrict the water flow through the by pass. We had talked over the phone and he was asking if he could use my car as a little experment. He related that he had worked on other Z's with the same problem but wanted to try this on mine. At the time I had him installed a new OEM thermostat and do his radiator service. The end result was a drastic reduction in temps.

[pantera1683]

http://forums.*************.com/c4-zr-1-discussion/259664-thermostat-cooling-discussion-pic-included.html[/URL]
http://i287.photobucket.com/albums/ll142/dynomite007/ZR1/A-THERM1-1.jpg


Link no workie.

[ScottZ95ZR1]

You must replace the asterisks in the link with "that other forum's name". For some reason links to the other forum are masked here....

[ScottZ95ZR1]

Yeah, what Cliff said. :mrgreen:

[scottfab]

either someone post the actual path of the "other forum" or post details of the modificaiton to the bypass. What washer? and where?
For the good of the ZR1 share.

UPDATE: Let me try at passing the link to the "other" forum.
Just replace the word "other" below with the word "corvette"
"http://forums.otherforum.com/c4-zr-1-discussion/259664-thermostat-cooling-discussion-pic-included.html"

The thread on the other forum is great. It will take a bit of reading to get it all but........ that's fine.
I hope somewhere it talks of the "washer" to add?? and where.

Below this line is a test of the replacement string for that other forum. All are variation on the name of that forum.
corvette-forum <-- addes a hyphen between the words
************* <-- other forum spelled correctly
corvette forum <-- used two words
corvettteforum <-- extra t in corvette

[Tyler Townsley]

either someone post the actual path of the "other forum" or post details of the modificaiton to the bypass. What washer? and where?
For the good of the ZR1 share.

If you want the thermo to work you have to make sure the bypass works, its how the warm water acts on it so that it opens. You cannot just block the bypass. In addition if you do anything that changes the water flow at higher RPM then you need to replace the radiator first as the stock radiator cannot handle the higher flow, thats why the bypass was developed.

If you are going to use the car in a racing application or for summertime use you can cut the thermo spring,
http://deliquescence.net/~tyler/misc/Thermo.jpg
AND replace the radiator with a higher flow unit. This modification will result in the coolest water temps. I ran this in Florida for many years and saw water temps on the interstate of 170 deg in 90+ weather. In town ran 190 200 deg.

Tyler

[ittlfly]

When did Marc do this experiment? It must be something he just invented :mrgreen:

Don't shoot the messenger..:mrgreen: I'm just relating what MH said to me over the phone. Mark had the car back in Jan '07 for about 3 months.

I guess a phone call to him would clear up the matter of the ''experiment'' if you are so inclined. :cheers:

[scottfab]

You cannot just block the bypass. In addition if you do anything that changes the water flow at higher RPM then you need to replace the radiator first as the stock radiator cannot handle the higher flow, thats why the bypass was developed.
Tyler

I agree you cannot just block the bypass. And you cannot just remove the radiator either. But then who would do that?
As for changing anything about the water flow and needing a better radiator? Well I wonder about that. Seems a very small change in flow maybe tolerated by the OEM radiator. And what is the pressure relief on the radiator reservoir for? Maybe at high pressure it releases but the volume it releases is not enough? dunno yet. I may run some experiments this summer. High rpm runs can be a problem when it's hot.

My main concern is being stuck in traffic when its 90+ out and the pavement is 100+deg. I may go with an aux fan or replace the OEM fan with a higher flow one. The old trick of turning on the AC so the second fan kicks in works to some extent so maybe I'll just "rewire" it.
More fan power (new fans) may just be the ticket. I've also seen aux fans mounted at the wheel well for getting better air flow but cutting holes is radical.