Hello,

I am working on a 1985 Z28. Car was original 5.0L TPI with 700R4. I swapped a 5.7L under the TPI setup and that is running well. I swapped in a T-5 from a 1986 IROC and that is running well. Stock 3:23 open diff.
Stock cast iron manifolds, y pipe and Flowmaster exhaust for Z28. Sounds good.

My issue now is cooling. I restored the AC system and converted to R134A.

When I did the AC system, I installed all new components. I purchased two 10" pusher fans and installed on the condenser. I then purchased an AMAZON 3 Core aluminum radiator with two 10" puller fans and a complete shroud. All four fans have independent relays off the battery and I use the original fan power lead to trigger the four relays. All four fans come on per the ECM set temperature (I think 185 or 190).

New 195 TStat.
New water pump
timing set 6DBTDC per FSM

I have a 5.7L Temp Send Unit for a 1979 C10 as that fits the 5.7 L head (1/2 NPT. The 305 Temp Sending Unit is 3/8 NPT.

I also think my gauge is ***** so I just purchased a New replacement on EBAY, waiting on that. Classic Industries was back ordered or would have ordered from them.

I have a Snap-on Scanner that can read the OBD1 data. ECM was reading 190 deg off the manifold Temp Sender when the dash gauges was over 220 in garage on idle so I know gauge does not match ECM.

Today in NJ was about 85 degrees. Drove 10 miles to gas station and gauge climbed over 220 reading but stayed there. Close to service station, it climbed to 260. We popped hood at station. No bubbling so figured bad reading.

Filled up and returned home. Gauge went well over 260/red zone and stayed there. We pulled over and popped hood, again no bubbling so felt pretty certain gauge reading was off.

Finally got home and pulled in garage. Coolant was rumbling through cap and bubbl;ing in overflow bottle slightly after this quick 20 mile jaunt.

Yes I am running the lower air dam. It was missing when I bought car. I installed a used one I got off a parts car.
Yes pusher fans are pushing and puller fans are pulling.

My plan is as follows:

1. Purchased a new Gates safety lever cap in case my current cap is not holding 16 psi. Maybe the Chinese cap on Amazon Radiator cant hold 16 psi.
2. Install new gauge when I get it.
3. Switch to the Camaro sending unit (purchased 1/2 NPT to 3/8 NPT bushing to make that switch).

Any thoughts on other things I can do to lower engine temp. Want to daily this car and run AC when necessary.

Pic of radiator I purchased/installed.

Thanks in advance.

 

Where you effed up was effing with it to begin with.

Amazon & eBay don't make car parts. Amazon & eBay sell a bunch of cheap made Chinese junk though. It probably would have worked just fine if you had left it the eff alone.

 

A 100% stock properly functioning cooling systems as GM designed it will keep the car cool driving down the road with the AC on at speeds of 35+ MPH with no cooling fans at all.

You could literally take the cooling fans off the car and throw them in the trash, and it will stay cool.

 

A sock cooling system will cool a built 350 fine. I'd pull the Amazon rad and reinstall a stock one.

 

If the amazon fans are no name brand i would throw them in the trash. SPAL, DERALE, and tru cool are some well known names for fans

 

^this is also a good point^

I had the same experience and went w spals.

 

^True...I've done it. For months if not years, back in "the day". I think your pusher fans are a restriction to air flow.

Also ran a sbc 400 with stock rad and it worked fine, too.

 

Was this the first 10 minutes you drove it since the swap or has it already been properly bled? Did you get the right rotation of pump for your belt drive?

I'd remove that radiator and fan setup immediately and replace with stock rad and dual fan arrangement.

 

With the stock setup, car was running hot. Figured I would try to increase cooling capascity with pusher fans and new radiator with dual fans/shroud. Stock 1985 has single fan and no shroud.

 

The 1985 does not have serpentine so does not have reverse rotation pump. Motor was rebuilt last year and run in on stand prior to install.

1985 has a single 15” fan with no shroud. I was trying to increase cooling capacity with new radiator, two pullers and two pushers.

I will swap in new Gates Cap and update gauge and sending unit before I do anything else.

 

If the car was hot w a stock setup something is wrong. I had a 10:1 comp 350 hp car w a stock cooling sys for 20 years and it was fine. It's not until I added blower/intercool did I have to upgrade stuff.

 

My next steps are to replace radiator cap, gauge and sensor to see if there is still an issue. I have been working on this car since February. It was abandoned/title surrendered at a shop by a person who gave up spending money to fix it. I have been surprised hew much little stuff was broke/missing that you would not expect…missing relays etc. My suspicion is the radiator cap is passing. The sensor is not the right one as the 350 takes a 1/2NPT and the 305 is 3/8 NPT and the dash gauge could also be faulty.

Should have all parts by weekend/early next week.

 

You have decreased cooling capacity by installing garbage parts.

 

I agree with previous posters that you downgraded your cooling system, but am not convinced you need to abandon the aftermarket and go back stock.

Sounds like the car has been badly sodomized by previous owners. The fact air dam was missing when you got it tells me they were the typical idiots who just ripped crap off because they thought it was not needed or they wanted to save a few ounces of weight.

Sounds like you have a pretty good idea how to care for and modify a car, just need some more opinions on tackling the problem. Got some good suggestions already, I would add you should check the entire air intake path to and through the radiator. Most or all of these cars had plastic shroud pieces forward of the radiator and foam weatherstripping to help seal the path of air and force almost all of it actually through the radiator. I would explore that before ripping out your aftermarket stuff. I'm betting you find more evidence of necessary crap getting ditched by previous owners.

 

I think the fans are at fault as well...

I think the stock fan or LS fans would be a better setup.

 

There is one more thing that has not been talked about that is important:So, we REALLY don't even know what "hot", "overheating", is, with this car. I'd shoot it w/a temp gun when it's "hot".

 

The gauge sender is in the block, so it’s going to read 20-30 degrees hotter than the coolant temp sensor in the tstat housing. Cooling performance is primarily limited by airflow. The factory rad has plenty of capacity, and air flows better through a single core. The issue with factory fans is GM using Dexcool which sludges up with age or if mixed with incompatible coolant. Mine had about 3 lbs of sludge buildup in the lower passages compared to a new oe rad. Best bang for buck is a 4th gen dual fan assembly. Drops in after trimming some plastic tabs. 95 degree days in traffic with AC and my Vortec 350 hasn’t ever passed 200F. I did a 3-relay 2-speed setup with switches set for 180 low and 195 high.

 

This is wrong, on two counts.
First, the gauge sender is not in the block.
Second, the coolant temp in the block is not 20-30* higher than in the stat housing. In fact, the block is about the coolest coolant temp location b/c it's the first place (in the engine) that the coolant goes to, after the radiator. The coolant in the tstat housing has gone through the block, up into and through the heads, and through the intake to the stat housing. So...that is ABOUT the hottest place for coolant temps, on average.



Weeeelllllllll....that ain't true either.
First, what's that got to do with "the issue with factory fans"??
Second, Dex cool does NOT "sludge up" with age. As a mechanic, and the boss of mechanics for the last 30+ years, I started running Dex in personal and Fleet, in ~1998. I/we have run it in everything from snowmobiles, up to 530hp snow cats and have never witnessed properly used and administered Dexcool sludge up....at all!
Yes, it used to have issues when mixed with incompatible coolants (that has since changed with a reformulation).
HERE is some good reading about Dexcool, with actual real world results included. Where's the sludge?
And THIS THREAD has a pic (3rd pics down, first post) of the inside of a HIGH mile radiator that had Dex in it. Where's the sludge?

But, for all of that; did the OP say he was running Dex anyway? I missed it and/or can't find where he said that....

 

OK, want to update all with my status.. This car has been plagued with multiple little things that I would not have expected. The previous owners ultimately surrendered this car at the shop doing repairs because either they had no more money or did not want to spend anymore.

Clearly the 3 core amazon aluminum radiator does not have the cooling capacity of the prior single core plastic tank radiator. I inspected the plastic radiator I took out and it has the GM logo on it so apparently it was an OEM replacement.
I replaced the radiator cap; with a new gates safety cap and no longer passing to the overflow. I put in a new gates 195 Tstat which i added a 1/16" bleed hole. I flushed and cleaned the GM radiator and put back in. I kept the aluminum double fan shroud from the Amazon 3 core figuring shroud was better than no shroud. I replaced the two chinese fans with Spal fans as suggested. I put a new temp gauge in the cluster and put a new sensing unit in the driver side head.

I have a Snap on Scanner that can take real time data

With the A/C off the car will cruise with the ECM coolant temp of the front of the TPI manifold at 195 +/- . The corresponding temp gauge readings are midway to 3/4 between 160 and 220.

On an 80 degree day in New Jersey with AC on, the temp gauge will be closer to 220 and climbing steep hill by my house will creep towards 240 but it restores to 220 when roads levels off.

The car is now driveable and I have been daily driving to work. Clearly the three core aluminum radiator was not as good as the GM single core. I ran both radiators with the SPAL Fans.

Car can idle in the driveway with gauge midway between 160 and 220.

Not sure how car would be on a 90+ degree day with AC, but wont see one of those till next June.

If there are any other suggestions to help car run a little cooler, I would like to know.

One thing I do note is the shroud only has the holes for the two fans. The four corners do not have any holes to let air flow pass. I could cut some hoes to allow air to pass.

 

Hopefully ditched the pusher fans as well

 

I did not. Still installed and running. They do
not appear to block a significant area on the condenser entrance. Why do believe they reduce system performance?

 

Oil Temps have a huge effect on coolant temps. A separate oil cooler would help. Oil typically wants to he hotter than coolant, and that puts a heat load into the cooling system with typical OEM oil cooling methods;
An OEM oil to water cooler puts the oil's heat directly into the coolant,...drives coolant temps up.
An OEM w/NO oil cooler? Well, the oil temps are absorbed by the block and that same amount of heat then gets transfered into? The coolant. Drives coolant temps up.

By using a completely separate oil to air oil cooler, you can remove that heat load of the oil from the cooling system entirely...while also tailoring it to get you the oil temps that you prefer.