Z was running hot - Notes on how I fixed it. - ZR-1 Net Registry Forums

Ccmano · 07-23-2006

This probably isn't a new issue to many of you, but I thought I'd share a few comments on how I resolved my hot running Z.
After owning the Z for a few weeks now I noticed that she ran on the hot side in traffic and particularly on very hot days with temps over 95'. Last week she almost overheated on me on a 103' day:willy: . After researching this site an the other ZR-1 sites out there I knew what I had to do. (Isn't the internet a great thing!)
As usual, I jumped in with both feet and pulled the radiator, hoses and t-stat out of the car. I found what all C4 owners eventually find, a clogged radiator and a thermostat on it's last legs. The hoses were marginal so I decided to replace them while I was there. You can find the "how to" elsewhere but here a couple of things I learned:
Those six little 7mm screws that hold the front of the shroud are a bear, but with patience you can get to all of them for removal. Removing the horn and air pump make getting to the upper passenger side screws much easier. Remember to move to spring thingys that the screws screw into, from the shroud to the part of the housing that stays in the car. This way you can put the screws in from the inside when reinstalling the shroud. There's alot more room to work from the inside.
Yes, you can take the radiator shroud out, without removing any of the A/C or Oil cooler lines, just lift the driver side while standing on the passengers side and work the shroud out from around the hoses. It comes out and goes back in with a little effort.
Removal of the hoses and t-stat housing is pretty straight forward except for the lower radiator hose. I found that by removing the fans with their housing, removing the serpantine belt and holding the belt tensioner back with a long half inch breaker bar, That gave me reasonable access to the hose clamp that attached the lower hose to the block. When installing the new hose there, just use a standard screw type clamp, it's much easier to install than the original type.
If you get this far and you haven't replaced the serpantine belt in some time or maybe it's never been done, go ahead and do it now. It dosn't get any easier. It's cheap insurance. They are available from any parts store.
I used a 180' t-stat from "Stant" #14068 as recommended by many and a set of new hoses from "White Racing". Kurt got them to me last minute in good order. (thanks Kurt)
Although the radiator cleaned up well, I ended up installing a new one. On final inspection of the original radiator I found cracks in the reinforcing webs around the lower outlet. I've read about this, again better safe than sorry, I got an new GM radiator. E-bay $149 shipped. Half the price of the local dealer.
I also added a Haibeck chip (needed an excuse)

but now the fans turn on earlier and at the same time, plus a few "other" things.
Everything else went back together normally. I found "Low Silica" coolant at my local CarQuest store (their brand) a nice to have for an all aluminium engine like ours.
Now that everything is back together she runs cool

as can be. Before she was in the upper quarter of the temp guage, now, right in the middle.
Thanks forum, for all the info..hope this gives a little back.
Hans

WB9MCW · 07-23-2006

EXCELLENT WRITE UP Ccmano... good job and thanx for the nice detailed post!

07-23-2006	#2
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: Z was running hot - Notes on how I fixed it. EXCELLENT WRITE UP Ccmano... good job and thanx for the nice detailed post! __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln

07-23-2006	#1
Ccmano Join Date: Jun 2006 Location: Sparks, NV Posts: 2,852	Z was running hot - Notes on how I fixed it. This probably isn't a new issue to many of you, but I thought I'd share a few comments on how I resolved my hot running Z. After owning the Z for a few weeks now I noticed that she ran on the hot side in traffic and particularly on very hot days with temps over 95'. Last week she almost overheated on me on a 103' day:willy: . After researching this site an the other ZR-1 sites out there I knew what I had to do. (Isn't the internet a great thing!) As usual, I jumped in with both feet and pulled the radiator, hoses and t-stat out of the car. I found what all C4 owners eventually find, a clogged radiator and a thermostat on it's last legs. The hoses were marginal so I decided to replace them while I was there. You can find the "how to" elsewhere but here a couple of things I learned: Those six little 7mm screws that hold the front of the shroud are a bear, but with patience you can get to all of them for removal. Removing the horn and air pump make getting to the upper passenger side screws much easier. Remember to move to spring thingys that the screws screw into, from the shroud to the part of the housing that stays in the car. This way you can put the screws in from the inside when reinstalling the shroud. There's alot more room to work from the inside. Yes, you can take the radiator shroud out, without removing any of the A/C or Oil cooler lines, just lift the driver side while standing on the passengers side and work the shroud out from around the hoses. It comes out and goes back in with a little effort. Removal of the hoses and t-stat housing is pretty straight forward except for the lower radiator hose. I found that by removing the fans with their housing, removing the serpantine belt and holding the belt tensioner back with a long half inch breaker bar, That gave me reasonable access to the hose clamp that attached the lower hose to the block. When installing the new hose there, just use a standard screw type clamp, it's much easier to install than the original type. If you get this far and you haven't replaced the serpantine belt in some time or maybe it's never been done, go ahead and do it now. It dosn't get any easier. It's cheap insurance. They are available from any parts store. I used a 180' t-stat from "Stant" #14068 as recommended by many and a set of new hoses from "White Racing". Kurt got them to me last minute in good order. (thanks Kurt) Although the radiator cleaned up well, I ended up installing a new one. On final inspection of the original radiator I found cracks in the reinforcing webs around the lower outlet. I've read about this, again better safe than sorry, I got an new GM radiator. E-bay $149 shipped. Half the price of the local dealer. I also added a Haibeck chip (needed an excuse) but now the fans turn on earlier and at the same time, plus a few "other" things. Everything else went back together normally. I found "Low Silica" coolant at my local CarQuest store (their brand) a nice to have for an all aluminium engine like ours. Now that everything is back together she runs cool as can be. Before she was in the upper quarter of the temp guage, now, right in the middle. Thanks forum, for all the info..hope this gives a little back. Hans __________________ 90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold.