Need to choose a new radiator

[1991ZR1]

Are the L98 and ZR1 radiators the same?
Are DeWitts and Fluidyne equal to each other?

I have a strange leak. It leaks after I turn off the engine. I ran the car with the air conditioner off to make sure it wasn't coming from condensation.

[tomtom72]

I think that they are the same radiator if you go to autozone and plug in the info in their parts locator.

Sorry I do not have any experience with either of the name brand replacement radiators you listed. I know that alot of people use DeWitts as an upgrade over a stock replacement. I do know that a standard replacement radiator that you get at a chevy store and/or an auto parts store usually comes with the auto trans cooler in the right side tank....no choice. The DeWitts has a discrete listing for auto or manual trans application. I would think that Fluidyne does the same.

I would think that it might be a prudent step to put a pressure tester on the system just to make sure it's the radiator (core &/or side tanks) that's leaking. Unless you saw the leak & are sure it's the rad?

:cheers:
Tom

[ZZZZZR1]

Are the L98 and ZR1 radiators the same?
Are DeWitts and Fluidyne equal to each other?

I have a strange leak. It leaks after I turn off the engine. I ran the car with the air conditioner off to make sure it wasn't coming from condensation.


ZR1 radiators are the same... You can purchase an OEM ZR1 radiator on ebay for $99 plus shipping ($60).

QB93Z (Jim) just purchased one and could give you more details on the other radiators.

[PhillipsLT5]

Went with Fluidyne per Hib
It has brought temps down here in AZ

[Jeffvette]

The current OEM replacement radiator you get is made for an automatic car. It has the provisions for the tranny cooler.

[FU]

Are the L98 and ZR1 radiators the same?
Are DeWitts and Fluidyne equal to each other?.
I used Fluidyne same as above. DeWitts also has a great Rad.

It leaks after I turn off the engine.

Pressure test the system. It's easy and you'll be suprised what may be found.

[Jeffvette]

Pressure test the system. It's easy and you'll be suprised what may be found.

You should be able to go to any of the parts stores that do rentals, and they will have a pressure tester for rent.

[Tyler Townsley]

If it is dead center of the car it may be the water pump rather than the radiator. GM deliberately chose not to put in an upgraded rediator in the ZR-1 and designed the bypass system to protect it from the higher GPM that Lotus designed for the car. Lotus spected the pump to flow 25 gal per min per 100 hp which is close to 100 GPM.

Tyler

[GOLDCYLON]

The radiators are exactly the same. As stated above the Automatic transmission lines are just not used and a standard radiator can be had as stated for $150 shipped to the door. The new OEM style radiator will work fine.

[1991ZR1]

I would think that it might be a prudent step to put a pressure tester on the system just to make sure it's the radiator (core &/or side tanks) that's leaking. Unless you saw the leak & are sure it's the rad?

:cheers:
Tom

Thanks guys.

I can't see where the leak is but it comes from the center under the radiator. It can be somewhere other than the center and running along the frame to the center. It's not the water pump because I would be able to see it. As far as I can see, it's not any hoses. The main hoses are Samco hoses and I doubt that they would leak.

With the car being 17 years old and having the original radiator, I figure it's a good time to change it anyway. Sounds like I can't go wrong which ever I choose or go with stock replacement.

[tomtom72]

I was thinking the same thing when I took out the rad on my 90 to clean it. Surprisingly it was in good shape as the original owner kept up with the maintenance on the cooling system and didn't use the car much. I was doing a samco hose kit and my oil cooler hose r&r project and decided it would be a good time to clean the cooling stack also.

Not to make work for you but here is a link that I found to be a very useful alteration/addition if you use your Z alot.
http://www.zr1netregistry.com/ZR1_radiatorscreen.htm

I average about 5K a yr and every week I get to see what junk would have gotten into my cooling stack.

Oh yea, thanks for the mention of Fluidyne....I completely forgot them in my thinking about where I will get my replacement radiator when the time comes.:thumbsup:

:cheers:
Tom

[GOLDCYLON]

Hmm im wondering if its the underside of the crossover tube or more likely the thermostat housing extension that is approx in the center next to the radiator is the culprit or the hose that connects to the TH housing on the underside.Further back in the center its gotta be the waterpump. I would get her up to temperature while on a jack stack and then look underneath.

[Aurora40]

FWIW, the DeWitts is on sale until 10/31. They also claim you no longer have to trim the fan shroud to use the rad.

[GOLDCYLON]

Any updates on the Radiator project? :happy1:

[1991ZR1]

Any updates on the Radiator project? :happy1:

No change yet. I just got back home from the SEMA show so I'm really tired. Also somewhat poorer. Maybe next weekend I'll put the car on jack stands and run it to try to see where the water is coming from.

[QB93Z]

The radiators are exactly the same. As stated above the Automatic transmission lines are just not used and a standard radiator can be had as stated for $150 shipped to the door. The new OEM style radiator will work fine.

I bought a "OEM" radiator on eBay that was supposed to work in the ZR-1. It is a Delphi product, Part # RA1138.

The radiator is the 1990-1996 style but all the ones in the system have the auto transmission cooler connections on the right end tank. The idea is that you don't have to hook up the auto trans cooler lines to install the radiator in a manual trans car.

BUT:

The problem is that the auto trans cooler in the right end tank blocks the opening where the radiator outlet hose connects. Here is a picture of the outlet:

http://i407.photobucket.com/albums/pp152/QB93Z/Radiator/DSC01698.jpg


The tan colored piece you see in the opening is part of the transmission cooler. There is less that 3/8" clearance between the opening edge and the tan piece.

I decided not to use the Delphi radiator because I think that the flow rate will be compromised by the restriction.

I could not find any of the OEM radiators that were for a ZR-1 (manual trans C4) so I bought a DeWitts radiator. It is a thing of beauty:

http://i407.photobucket.com/albums/pp152/QB93Z/Radiator/DSC01700.jpg

As soon as I get my Samco hoses I will be putting it in.

Jim

[Jagdpanzer]

Jim,
Which Z is getting the new radiator?

[QB93Z]

Jim,
Which Z is getting the new radiator?

The Red '90. It is leaking from the right end tank. It started leaking after the first time I did a nice hard acceleration.

Hey Phil, are you coming to Mason Dixon Dragway this Saturday?

Jim

[Jagdpanzer]

Hey Phil, are you coming to Mason Dixon Dragway this Saturday?

Jim

Jim,
You bet!
Already have the new set of MT DRs on the back plus the skinny A-molds I got from Pete last summer shod with 5.3" wide Hoosier Pro Street radials on the front.
This weekend I pulled the plenum and put a new set of Accel injectors in. While at it also removed the coil plate and starter to titivate (that's sailor talk for make smart or spruce up for you lubbers out there) the valley. Checked out the secondary vacuum system out to make sure it was tight and working properly and changed out the inline fuel filter. Still have to put in a new set of NGK TR55IX Iridium sparklers then this Torch Red ZR-1 from Virginia will be ready to wage 1320 warfare with you boys from MD at Mason Dixon Dragway this Saturday.
This will be my first outing to the strip with the Z so I'm not sure what it'll do, probably low thirteen's or high twelve's at around 110 mph is my guess. Let pray the weather holds. If lot of Zs show up maybe we can declare this event the inaugural North verses South ZR-1 Mason-Dixon Line showdown.

[GOLDCYLON]

Jim when you put those Samcos on remember you have to seperate the top off the TH housing to get the lower short hose on then reinstall the top of the TH housing. Wont work any other way.

You are correct you wont find a MT radiator in the inventory anywhere. And... the Delphi is GMs one size fits most solution. So far its been working great for me. Did you have to cut the shroud with the Dewitts?
GC

[QB93Z]

GC, Thanks for the tip about the thermostat housing. I was planning on replacing the thermostat anyway.

I have not done the install yet because I am still waiting for the Samco hoses I bought on the registry site to be shipped.

And, yes, the DeWitt instructions say to trim the shroud.

Jim

[Aurora40]

Hmm, I'm interested to hear about the DeWitts install. Their website says they no longer require the shroud to be trimmed:

http://www.dewitts.com/pages/productdetail.asp?ProdID=325

NEW FOAM SEAL KIT & METAL SPACER BARS INCLUDED!
We now include custom foam seals & spacer plates so no shroud cutting is required.

[GOLDCYLON]

I think Jim did his Rad before this newer version was released. Ive heard that stated before but I havent seen a member install a "Brand new" Dewitts lately. Would be great if true.

[1991ZR1]

I found out that the radiator is leaking along the tank on the driver's side of the radiator. So at least now I'm sure that I need to replace the radiator.

While I was looking for the leak, I looked under the front of the car. It's amazing that I wasn't having over heating problems. There was a news paper covering most of the front of the air conditioning condenser. I guess I have to check that area every so often.

[tomtom72]

I found out that the radiator is leaking along the tank on the driver's side of the radiator. So at least now I'm sure that I need to replace the radiator.

While I was looking for the leak, I looked under the front of the car. It's amazing that I wasn't having over heating problems. There was a news paper covering most of the front of the air conditioning condenser. I guess I have to check that area every so often.

This is from the mothership & I did this as soon as I took delivery of my Z and I can say that it works. Check it out.
http://www.zr1netregistry.com/ZR1_radiatorscreen.htm

:thumbsup:
Tom

[Dynomite]

Hmm, I'm interested to hear about the DeWitts install. Their website says they no longer require the shroud to be trimmed:

http://www.dewitts.com/pages/productdetail.asp?ProdID=325

For the Dewitts A90M radiator, in order to install the thicker core, a small piece (1/4 inch) of the two upper cushions must be trimmed out. The lower cushions do not need any modification. Enclosed with the radiator are two aluminum spacer plates and hardware. These plates need to be installed between the fan shroud and housing, using the longer bolts supplied in the kit. This is required to prevent the fan shroud from damaging the thicker core.

Also enclosed are the two self-adhesive foam seals. Stick one of the seals on the top of the radiator core and one on the bottom.

Install the radiator as normal and re-assemble the top cover with the modified cushions.


If this is not the case, I will take a picture and let you know when I install my Dewitts radiator :D

Anything will be simpler than removing those six 7mm screws :cheers:

[QB93Z]

Here is a picture of the "spacer" that I got with my DeWitts radiator that I installed in my 1990 ZR-1 last December.

http://i407.photobucket.com/albums/pp152/QB93Z/Radiator/DeWittsinstalledin1990ZR-11.jpg

The spacers, one top and one at the bottom are aluminum bars about 3/8" by 1" by ~36". I guess if you paint them black they wouldn't be so noticable.

My recommendation is to trim the shroud. That is what I did when I installed a Ron Davis Radiator in my 1993 ZR-1 about 9 month ago.

Jim

[A1990]

Why did you go with Dewitt's this time over the Ron Davis model?

[QB93Z]

I installed the Ron Davis radiator in the 1993 after I put the DeWitts in the 1990 because I liked the construction of the Ron Davis radiator better. The difference has to do with the way that the radiator seals the space above and below the body of the radiator. Here is the DeWitts unit:

http://i407.photobucket.com/albums/pp152/QB93Z/Radiator/DSC01700.jpg

Notice the two support flanges that rise above the radiator body at the outer ends of the radiator. Since the shroud does not have slots or openings for these flanges, the space between the flanges has to be "sealed" with a 2" by 2" foam strip (provided by Dewitts).

Here is the Ron Davis radiator:

http://i407.photobucket.com/albums/pp152/QB93Z/Radiator/DSC01882.jpg

Notice that the top edges of the body section extend to the same height as the flanges. This means that the radiator installs tight against the shroud without requiring a foam seal.

The Ron Davis unit costs more. Both units were very well constructed and easy to install.

Operationally, both units perform well and I do not notice a difference between them.

Jim

[Dynomite]

My recommendation is to trim the shroud. That is what I did when I installed a Ron Davis Radiator in my 1993 ZR-1 about 9 month ago.

Jim

I assume you are suggesting that if you trim the internal part of the fan shrouds so they do not interfere with the radiator you do not have to use the spacers?

[QB93Z]

I assume you are suggesting that if you trim the internal part of the fan shrouds so they do not interfere with the radiator you do not have to use the spacers?

That is correct. To install either the DeWitts or the Ron Davis radiators, you have to account for the thicker tube section, either with spacers or trimming the fan shroud. I have repalced two radiators: one with spacers and one by trimming the shroud.

My theory now is that the trimmed shroud cannot be seen. The radiator I install now will last the lifetime of the car. If I ever did have to replace the radiator again I would use one of thicker radiators again.

Jim

[QB93Z]

Another thought.

If you are still deciding between a stock-type radiator (like the Delphi model that "works" in both auto and manual transmission C4's) consider this.

I have owned a lot of cars in the last 40 years. I have only had to replace two radiators on all those cars. Both failures occurred on GM stock radiators with the plastic end caps. One in a Trans Am and one in a ZR-1.

Jim

[Dynomite]

Another thought.

If you are still deciding between a stock-type radiator (like the Delphi model that "works" in both auto and manual transmission C4's) consider this.

I have owned a lot of cars in the last 40 years. I have only had to replace two radiators on all those cars. Both failures occurred on GM stock radiators with the plastic end caps. One in a Trans Am and one in a ZR-1.

Jim

I got the Delphi and noticed the restriction....started calculating and it appeared that was a head loss I should not have (especially since I did not need a transmission oil cooler) and I came upon your insight to that issue herein. I will get either the DeWitts or the Ron Davis radiator :thumbsup:

I will use the Delphi on something else in my "car lot" :sign10:

[QB93Z]

I bought the Delphi radiator from an eBay dealer. When I decided that it was not the one I wanted to use, the dealer took it back and credited the refund against the price of a DeWitts unit. :thumbsup::thumbsup:

Good luck swapping out the radiator. It is one of those jobs that can lead to lots of "well while I'm in here I might as well.....

Jim

[Dynomite]

I bought the Delphi radiator from an eBay dealer. When I decided that it was not the one I wanted to use, the dealer took it back and credited the refund against the price of a DeWitts unit. :thumbsup::thumbsup:

Good luck swapping out the radiator. It is one of those jobs that can lead to lots of "well while I'm in here I might as well.....

Jim

Jim....you and I think alike :sign10:...after working on those six 7 mm screws for half an hour...that is exactly what I was thinking.....so I removed water pump and pressure washed whole front end :thumbsup:

I am now thinking again....what else can I do now that I am in here :D

[Dynomite]

That is correct. To install either the DeWitts or the Ron Davis radiators, you have to account for the thicker tube section, either with spacers or trimming the fan shroud. I have repalced two radiators: one with spacers and one by trimming the shroud.

My theory now is that the trimmed shroud cannot be seen. The radiator I install now will last the lifetime of the car. If I ever did have to replace the radiator again I would use one of thicker radiators again.

Jim

I think the DeWitts A90M is $495 and the Ron Davis 1-16CV8996 is $540. Both are well constructed radiators :thumbsup:

Both radiators look great and the Ron Davis seals itself at the top (and bottom?) so you pay a bit more. I doubt the Ron Davis radiator comes with the spacer so you definitely have to trim the fan shroud for the Ron Davis which I would do anyway for either radiator as per your suggestion.

Neither model mentioned has the transmission oil cooler :thumbsup:

[GOLDCYLON]

Another thought.

If you are still deciding between a stock-type radiator (like the Delphi model that "works" in both auto and manual transmission C4's) consider this.

I have owned a lot of cars in the last 40 years. I have only had to replace two radiators on all those cars. Both failures occurred on GM stock radiators with the plastic end caps. One in a Trans Am and one in a ZR-1.

Jim

As the beast get old the plastic ends tend to swell. Why manufacturer ever switched to plastic I dont know. But when your replacing your radiator on your 91 Z for the first time its potentially the original 18 year old original radiator so maybe they were on to something :dontknow:

[QB93Z]

I agree Daryll. There are a lot of cars with a lot of miles on plastic end cap radiators. My '90 ZR-1 was at 73K and my '88 Trans Am was over 100K when I had to replace the radiator.

But as in any "what should I buy" decision, You have to pick something to narrow down the field.

Jim

[GOLDCYLON]

I agree Daryll. There are a lot of cars with a lot of miles on plastic end cap radiators. My '90 ZR-1 was at 73K and my '88 Trans Am was over 100K when I had to replace the radiator.

But as in any "what should I buy" decision, You have to pick something to narrow down the field.

Jim


Concur. I consider myself lucky this time around. 100% of my maintenance and repair efforts go towards my prime mover vs. my hobby car. The ZR-1 is one hell of a prime mover/hobby car. I get compliments on it all the time and most cant beleive the car is almost 19!!!

[Dynomite]

I removed the ole radiator from my 91' Z and during the removal remember removing this from the bottom where the radiator was positioned after I removed the radiator :happy1:

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

I am about to fit my new Ron Davis radiator and cannot remember where or how that plastic fits in the bottom or even what it is for :dontknow:

[QB93Z]

If what you pictured is a thin, flexible material, it goes on top of the upper shouud, before you put the air filter box in. It is low and forward. I basically covers the small gap between the radiator shroud top and the engine compartment side of the front bumper. I don't remember any attachment devices. It just seemed to be laying there. It must be held in place by the air filter housing.

Jim

[Dynomite]

If what you pictured is a thin, flexible material, it goes on top of the upper shouud, before you put the air filter box in. It is low and forward. I basically covers the small gap between the radiator shroud top and the engine compartment side of the front bumper. I don't remember any attachment devices. It just seemed to be laying there. It must be held in place by the air filter housing.

Jim

Yes...it is thin flexible material.....so prolly this fell down to the bottom as I removed the shroud :thumbsup:

Say...Jim......this server may be slow but you respond very fast...appreciated :worship:

[QB93Z]

:thumbsup::thumbsup:

Good luck getting it all back together.

Jim