? on 70 300hp with a/c heater hoses

[Steve D.]

The guide states that these hoses may or may not have the GM logo. Which have you guys seen more often? Logo or non logo.

[Terry M.]

Re: ? on 70 300hp with a/c heater hoses

I have NEVER seen a 1970-72 with original heater hoses with the GM logo on them.

[Don L.]

Re: ? on 70 300hp with a/c heater hoses

I have NEVER seen a 1970-72 with original heater hoses with the GM logo on them.

Terry, knowing that you've seen MANY 1970-1972 heater hoses, what HAVE you seen? Feedback appreciated.

Steve, FWIW, lacquer thinner will remove the GM logos. I believe you should be looking for raised ribs on your hoses for the original look. Of course, you need to be very careful when using lacquer thinner around any painted finish. It'll eat paint right up

[Terry M.]

Re: ? on 70 300hp with a/c heater hoses

Last chance before I join the road tour.

Groves, not raised ribs. No logs. Sometimes a single letter repeated along the length of the hose. The letter depends on AC/not AC and engine type. We don't have a good list of the letters. Anyone with original heater hoses from 1968 to 1972 can add to the data base.

BTW: The OP didn't ask, but I would accept a GM logo (on one hose only, and I don't recall which, ask the 1967 guys. I haven't had my coffee yet.) for early and maybe all of 1968.

[Robert S.]

Re: ? on 70 300hp with a/c heater hoses

This info. is on a 74' with A/C. I wanted to submit it to save the data. I had to replace what I think were the original heater hoses when I replaced the heater core. I saved the hoses and here is how they are marked. Neither have any GM markings. Both hoses have signs of use of tower clamps at the engine end and spiral clamps are the heater core end.

Small hose - has molded bends at both ends, has 3 grooves (or 4 ridges depending on your viewpoint) and has a single white stripe running the length. The following markings are at the hose ends only: 78E62 EBD 04084 X129 X8.

Large hose - has molded bend on one end, has 3 grooves (or 4 ridges depending on your viewpoint) has has a double white stripe running the length.
The followng markings are along the hose in areas that interrupt the double white stripe: EPDM EB D12013.

[Mark D.]

Re: ? on 70 300hp with a/c heater hoses

Here are some examples of heater hose markings from 68 thru 72. As my friend states, it's going to require some research to determine what they mean, specifically.

This one from Terry's heater hose...



And another from a 69 SB...



This is a repop stamp I put on my 69 L89. I have no idea if it is right or wrong...

[Terry M.]

Re: ? on 70 300hp with a/c heater hoses

Gosh Mark, could you have made those pictures any larger?

BTW: First image is from a 1970 LT1. And I think there IS a difference between grooves and raised ribs, and it has nothing to do with your point of view. I have impaired depth perception and I can tell the difference.

[Mark D.]

Re: ? on 70 300hp with a/c heater hoses

Gosh Mark, could you have made those pictures any larger?

I know...what's up with that? I made that post using my iphone while sitting in the cockpit of a 737. Maybe some curious electrons...