LT4 Radiator Cap

[Floyd B.]

I don't have my '94 - '96 Judging Guide yet - I'm going to pick one up at the Kissimmee meet, so I can't look this up at the moment. My LT4 is currently sporting an RC36 cap on the surge tank. I have seen references to using RC27 as the current service replacement. Did RC27 supersede RC36? Is RC36 the original cap for the LT4?

[Pat M.]

Re: LT4 Radiator Cap

Floyd - my one-owner LT4 has the RC27 on it, and I feel certain it is original to the car.

Oddly, the new manual does not specify the correct LT4 cap. The radiator cap section begins "The 1994, 1995, and 1996 LT1 and LT5 Corvette radiator caps are AC Type RC36." The rest of the paragraph does not address the LT4.

[Floyd B.]

Re: LT4 Radiator Cap

Floyd - my one-owner LT4 has the RC27 on it, and I feel certain it is original to the car.

Oddly, the new manual does not specify the correct LT4 cap. The radiator cap section begins "The 1994, 1995, and 1996 LT1 and LT5 Corvette radiator caps are AC Type RC36." The rest of the paragraph does not address the LT4.

Thanx Pat. I'm the fourth owner of my LT4 if you do not count the two auto dealers that held the title to this car. The RC36 appears to be aged to about the same level as the other "consumable" parts in this car. It's quite original and apparent that none of the previous owners changed out any parts unless they had to. I would guess that this surge tank cap is more likely to be orginal than not but that's far from certain. If I search the AC Delco catalog online, it lists the RC27 as the replacement part.

[Pat M.]

Re: LT4 Radiator Cap

Interesting.

Only one mechanic who is a good friend has worked on my 8K mile car since new, and he knows very well how NCRS-anal I am. I cannot concieve that he would ever have changed the cap without telling me, and in fact, there was only ONE time to my knowledge the cap has ever been removed. What are the odds he lost it that one time?

Hopefully other LT4 owners can add to this discussion.

[Jim T.]

Re: LT4 Radiator Cap

My original owner 1996 Corvette has had nothing done under the hood by anyone else since it left the showroom floor. The surge tank pressure cap is a RC27 and the original one delivered on the car.

[Joe L.]

Re: LT4 Radiator Cap

I don't have my '94 - '96 Judging Guide yet - I'm going to pick one up at the Kissimmee meet, so I can't look this up at the moment. My LT4 is currently sporting an RC36 cap on the surge tank. I have seen references to using RC27 as the current service replacement. Did RC27 supersede RC36? Is RC36 the original cap for the LT4?

Floyd-------


ALL 1996 Corvettes, LT1 and LT4 alike, originally used the RC-27 radiator cap. However, not all RC-27's are "created equal". There have been several GM part numbers for the RC-27 over the years. The original part number used on a 1996 was GM #6410427. The RC-27 is still available under, currently, GM #10409635. However, that cap, while 100% functional for the application, is NOT configured like an original RC-27.

[Floyd B.]

Re: LT4 Radiator Cap

Would someone be kind enough to post a picture of their original RC-27 so that I know what I'm looking for?

Thanx

[Pat M.]

Re: LT4 Radiator Cap

Here's mine:

[Floyd B.]

Re: LT4 Radiator Cap

Thanx Pat. That helps.

[Joe L.]

Re: LT4 Radiator Cap

Thanx Pat. That helps.

Floyd-------

...and here's a photo of an RC-36, aka GM #6410785. It replaced the original RC-27, aka GM #6410427, in April, 1997. Later, the RC-27 "came back" and is currently available under RC-27 OR GM #10409635. As I mentioned previously, though, the configuration is absolutely nothing like the original.

Is it possible that an RC-36 might have been used alternately in PRODUCTION for 1996 Corvettes? Yes, I'd say it's possible.

What's the difference between an RC-27 and an RC-36? I don't know.

[Floyd B.]

Re: LT4 Radiator Cap

...Is it possible that an RC-36 might have been used alternately in PRODUCTION for 1996 Corvettes? Yes, I'd say it's possible.

Joe,

Thanx for the information. Since I'm the fourth owner of this car and have very little knowledge/documentation of its life prior to my ownership, I'm going to have to assume that my car is not the exception. The original RC-27 as pictured by Pat was mostly likely replaced with the RC-36. I'll have to search for an original RC-27.

-Floyd-