Proper radiator cap for L98

[TedC]

The radiator cap that is on my 1989 L98 is an AC Delco RC-44. Cap states 17 PSI. I've confirmed that is the right cap for the L98 using several different vette parts catalogs. Yet the GM service manual states the cap pressure relief should be 15 PSI. After a little more research it looks like the LT-1 uses a 15 PSI rated cap (RC-27 or RC-36). An aftermarket cap at AZone is rated at 16 PSI, and is the same cap for either the L98 or a LT-1. I'm not sure a few PSI makes any difference, but a little surprised that the GM manual states 15 PSI when the recommended cap is 17 PSI.

 

[TedC]

Had to pick up a part at the Chevy dealership and asked them to see what cap they list for a 1989 vette. GM parts system showed two different caps for years 1985-90 (L98); RC-44 with a 17 PSI relief and a RC-81 with a 15 PSI relief. Both are still valid parts and can be ordered. Aftermarket caps by stant or gates are rated at 16 PSI.

 

[joshwilson3]

I went with Stant that has the pressure lever on it. The dealer said theirs only had the regular non-lever.

I like having the lever there so I got the Stant cap.

A higher PSI cap will raise the boiling point of the water. So, I'd say 17 would work fine.

 

[TedC]

I ordered a RC-81 and received an RC-33. It states 15 PSI. I'm trying it out. I don't expect any differences. But at least the PSI spec now matches the GM service manual.

 

[joshwilson3]

I ordered a RC-81 and received an RC-33. It states 15 PSI. I'm trying it out. I don't expect any differences. But at least the PSI spec now matches the GM service manual.

Did they offer one with a pressure release lever?

 

[TedC]

No. Very similar look to RC-44 with smaller cap ears. I've only seen the release lever on aftermarket units.