Piston Slap: Deffo Not Your Father's Oldsmobile!

Long time listener, first time caller. I have a 1982 Oldsmobile 98 Regency Brougham, that last summer I ripped the 307 out of. It now has a Chevy ZZ4 crate motor, backed by a TH 350 transmission. (Gasp! My hero!!! – SM)

My problem now is the car overheats if it is sitting still. I have a stock sized radiator (for the 307) installed, backed by a pair of electric 12″ fans. The fans are rotating in the proper direction, and do turn on and off properly.

My question now is: do I add more radiator (which would mean fabricating new mounts, lots of other stuff), or switch to a mechanical fan? I would need to go with a reverse rotation mechanical fan as I have the serpentine belt pulley kit on the motor. Do you think the fan alone will fix the problem? My other question is I only have about 1000 km on this engine, could it just be some trapped air in the coolant system?

Please reply quickly, as I am looking to start rolling in the car now that winter is done here in Winnipeg.

Thanks, Paul.

Sajeev answers:

First off, lemme say these vintage Olds 98s and Buick Electras are so much cooler than comparable Panthers. Second, OMG SON ZZ4 98 RESTOMOD FTW SON!

Now, how old is the radiator? You probably just need a new one, a OEM replacement. Radiators get clogged with age, and my first comment is to replace what you got if you do not know how old it is.

Once again, I love your restomod! Early 80s GM sedans deserve the attention you are giving. This is the real definition of Panther Love, fixing those often misloved American icons from our now unfortunate past. But, now we have crossover utility vehicles. So all the best to you.

Paul writes:

Hello Sajeev, thank you for the reply. The rad is brand new, installed at the same time as the engine. Any other ideas you have would help.

Thanks Again, Paul.

Sajeev answers:

How many CFMs (cubic feet per minute) do the fans push? You might want to see if they flow as well as the Lincoln Mark VIII electronic fan, as it is an upgrade for many vehicles, and maybe that’s what you need. See what CFMs it flows for sure.

Paul writes:

Hello Sajeev, the fans are not rated for CFM. I think I am going to go with the mechanical fan, and see what happens. I will make sure to update you with how well it works.

Thanks, Paul.

Sajeev concludes:

There’s nothing wrong with having a mechanical fan, but I’m starting to wonder if that isn’t the problem. Yes, perhaps you didn’t “burp” the system properly and there’s an air bubble in it. Definitely run the Olds (from a dead cold start) with the radiator cap removed and the heater on. Let the system circulate and as it gets up to operating temperature, you should see bubbles escaping from the radiator. Top off the system right there, and in a minute or two, put the cap back on when it starts to dribble out the top of the radiator.**

Perhaps the radiator cap isn’t strong enough to keep correct pressure, or maybe the thermostat is defective…or maybe who knows from our vantage point! But we all wish you luck on this unbelievably awesome restomod project. Dang.

**Not applicable on newer vehicles, as you can’t even see the radiator. The same technique applies, but you have to remove the radiator cap from the remote fill reservoir instead. And maybe from another fill/bleed point, ALWAYS RTFM WHEN IN DOUBT!

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry.