Heater box sealer

[Gene M.]

Re: Heater box sealer

Terry,
There are enough original c2 examples out there to support the practice of "goop" as well as cars without "goop". This leads to the conclusion from existence of both leaker fixes and cars that did not leak (at least in the heater box area). I'm sure John Hinkley or Mike Hanson can chime in on the practice back in the day.

[Nick C.]

Re: Heater box sealer

I have a searchable PDF version of the '65 AIM...It does mention a sealant on page 227, I'm not sure this is the correct one.


I couldn't find anything in the AIM about a leak test either, other than the A/C system (Freon).

It's is documented in John's amazing Assembly Process document on page 22.

http://www.michiganncrs.org/index_assets/CorvetteAssyProcess.pdf

Edit: I searched for "Water" and turned up this in the AIM.



Mike

Perhaps we are getting somewhere.

Maybe not. Obviously I misunderstood what the original poster meant by leaker fix. From emails and comments received over the years so do many owners and restorers. The only way I could make sense of it was to assume it was applied to help keep fumes out of the cabin.

If some agree application of liquid sealant to firewall surfaces occoured during C2 TFP, we need to isolate qualifiers. Why, where, how and when?

Were decisions made on the production line to apply or not apply? Was it haphazard? was it done post water test only to cars that leaked?

Aware of the AIM exterior water test, but not aware of a water test that sprayed water directly on the firewall. Was this exterior spray test done with hood open or closed? My guess is closed...but I was not there. We will have to hear from those directly familiar with the process.

[Terry M.]

Re: Heater box sealer

I just had a chance to read the below discussion. I guess I will stay away from midyears now.

[Chris E.]

Re: Heater box sealer

Nick, take a look at the "nozzle locations" in the image you just quoted, and it looks like there were both "overhead" and "under body" nozzles referenced. I would think it an easy leap of faith to say that an underbody nozzle would reach up the firewall and potentially get water inside the passenger side of the interior, through a poorly sealed heater box assembly.

For what it is worth, when we took my car apart, it did not have any evidence of the black goop, so I didn't put it back on the car.

Here is a picture from a 63 coupe. I don't see the splash shields in place (not sure if 63s had those or not). Regardless, even with the shields in place, if you have a high pressure nozzle shooting water straight up, it might make its way into the cabin if that heater box isn't sealed right.

9076548_59.jpg

[Nick C.]

Re: Heater box sealer

No issue with some 67's getting sealant and some not. Always understood that and never deducted for its absence or presence if typical factory material, NOT rope caulk or any of the other bogus stuff seen. NTP material deserves a fair deduct according to our originality based matrix judging system.

I will say I have driven and ridden in a fair number of midyears in heavy rain and snowstorms. I do not recall firewall heater box water leaks as an issue. Inner fenders and properly installed splash shields kept the firewall and upper engine fairly dry.

Windshields, Side and rear glass, cowls, front and rear of door, rear decks are typical trouble spots. Engine Firewall vapor leaks with windows up were sometimes (often) issues. Hence my dislike of the use of the term leaker fix when it is really sprayed sealant. Just a personal issue with semantics.

[Gene M.]

Re: Heater box sealer

I had saved this along with other mid year assembly line explanations. I can not recall if it was on this web site or from some article written by John. There may have been more with it but this gives ya the history behind the "gooey heater box stuff":

"The gooey, runny black stuff was a water-test repair sealant that was used in repair and intermittently on the main line; it wasn't part of the normal heater blower case installation." John Hinckley

[Chris E.]

Re: Heater box sealer

Is the wording in the judging manual going to be edited to be more obvious about this subject? I pretty consistently get hit for NOT having the black goop on my heater box. 1 point. Not a huge deal, but when you can only afford to give up 135 points on the whole car for Duntov, each point matters.

[Nick C.]

Re: Heater box sealer

Is the wording in the judging manual going to be edited to be more obvious about this subject? I pretty consistently get hit for NOT having the black goop on my heater box. 1 point. Not a huge deal, but when you can only afford to give up 135 points on the whole car for Duntov, each point matters.

We have a procedure for submitting CTIM&JG revision suggestions, detailed in the Foreword of each CTIM&JG. Posting on the TDB may garner some attention, but is not really proper procedure. Many NTL's do not monitor the TDB on a daily basis. Your concern may quite simply be overlooked. That said, review post #10. If you wish to propose a revision, please send to the NTL responsible, formatted as a CTIM&JG entry. Include any supporting evidence and documentation. "My car had" is of limited value; a VIN survey of original cars more useful. AIM references, photos, GM documentation, etc all add value to a proposal. A properly submitted proposal will be considered and reviewed by responsible revision team members for inclusion in the next CTIM&JG.

With regard to judging questions on field, proper protocol is detailed in the current edition of the Corvette Judging Reference Manual, Owner's advisories also contain information on how to handle issues while at an event.

[Chris E.]

Re: Heater box sealer

We have a procedure for submitting CTIM&JG revision suggestions, detailed in the Foreword of each CTIM&JG. Posting on the TDB may garner some attention, but is not really proper procedure. Many NTL's do not monitor the TDB on a daily basis. Your concern may quite simply be overlooked. That said, review post #10. If you wish to propose a revision, please send to the NTL responsible, formatted as a CTIM&JG entry. Include any supporting evidence and documentation. "My car had" is of limited value; a VIN survey of original cars more useful. AIM references, photos, GM documentation, etc all add value to a proposal. A properly submitted proposal will be considered and reviewed by responsible revision team members for inclusion in the next CTIM&JG.

With regard to judging questions on field, proper protocol is detailed in the current edition of the Corvette Judging Reference Manual, Owner's advisories also contain information on how to handle issues while at an event.

Understood Nick, thanks for the clarification and the reminder.

[John M.]

Re: Heater box sealer

Seeing as most or all C3s have it, including mine, I would say that the primary purpose of the goop was to keep water out of the cabin, probably and easier to do function than keeping gases out. My C3 leaks in a few places in the rain, including the firewall, clutch rod or speedo cable or something over there.

[Doug L.]

Re: Heater box sealer

I logged on to search the TDB for information on how to tackle a coolant leak at the heater and this was the latest thread. I almost went out to buy a lottery ticket.

After reading the thread it seems to me that any such sealant applied around the heater to firewall interface, on C2s at least, probably has nothing to do with coolant leaks. There are wells below the grills where the wiper shafts exit. Water (rain, snow, car wash, etc.) will enter the wells through those grills and should drain out the sides of each. However leaves or other debris could block the drains. Other points of exit would then be bolt holes through the firewall for the hood catches or the brake booster. If water find its way out of the wells though one of those openings it could flow down to the top edge of the heater assembly, and will probably flow into the front footwell. My guess is that the sealant being discussed is to prevent such water from entering the footwell where the carpet will probably absorb it and go un-noticed until it starts smelling or someone rides in their bare feet. That's my guess.

Now to my problem: coolant leaking at the connection between the upper heater hose and the upper heater pipe at the firewall. At first it was a trickle. I decided I didn't want or need a working heater given the weather here in South Florida, so I tried to plug the 2 pipes. I found a rubber plug that seems to have plugged the lower heater pipe while allowing me to install the heater hose and clamp. However because of the difference in size between the 2 hoses/pipes I tried using a plastic plug stuck into the upper pipe. That one leaked as soon as I started the engine. I think the problem is the shape of the heater pipes. They seem to be copper and have been bent and dinged through the years. My guess is that there is a small dimple that is allowing water to pass between the outer surface of the pipe and the inner surface of the hose. Is there some sealant I could use in this innerface to prevent leaks? I checked the heater core for leaks before installing it and found none.

[Terry M.]

Re: Heater box sealer

I logged on to search the TDB for information on how to tackle a coolant leak at the heater and this was the latest thread. I almost went out to buy a lottery ticket.

After reading the thread it seems to me that any such sealant applied around the heater to firewall interface, on C2s at least, probably has nothing to do with coolant leaks. There are wells below the grills where the wiper shafts exit. Water (rain, snow, car wash, etc.) will enter the wells through those grills and should drain out the sides of each. However leaves or other debris could block the drains. Other points of exit would then be bolt holes through the firewall for the hood catches or the brake booster. If water find its way out of the wells though one of those openings it could flow down to the top edge of the heater assembly, and will probably flow into the front footwell. My guess is that the sealant being discussed is to prevent such water from entering the footwell where the carpet will probably absorb it and go un-noticed until it starts smelling or someone rides in their bare feet. That's my guess.

Now to my problem: coolant leaking at the connection between the upper heater hose and the upper heater pipe at the firewall. At first it was a trickle. I decided I didn't want or need a working heater given the weather here in South Florida, so I tried to plug the 2 pipes. I found a rubber plug that seems to have plugged the lower heater pipe while allowing me to install the heater hose and clamp. However because of the difference in size between the 2 hoses/pipes I tried using a plastic plug stuck into the upper pipe. That one leaked as soon as I started the engine. I think the problem is the shape of the heater pipes. They seem to be copper and have been bent and dinged through the years. My guess is that there is a small dimple that is allowing water to pass between the outer surface of the pipe and the inner surface of the hose. Is there some sealant I could use in this innerface to prevent leaks? I checked the heater core for leaks before installing it and found none.

Bubba usually removes the heater hoses and installs a U shaped hose of the larger size between the water pump and the intake manifold. Double clamps on the smaller fitting (water pump I think) and move on.

[Doug L.]

Re: Heater box sealer

Hasn't been judged yet or I would do exactly that, or install a shutoff valve in one or both hoses.

[John M.]

Re: Heater box sealer

Doug, How about a couple of tapered rubber or silicone plugs, tight fit in each hose with some permatex shoved far enough into the hose to leave enough space to get them back over the heatercore outets. check McMasters.
I've never tried this.

[Harry S.]

Re: Heater box sealer

I took some 3/4 inch copper, two 90's and some straight and made a U. I connected the two hoses together at the firewall and hose clamped them. This way I could drive the car as I rebuilt the heater box (big hole) and changed the core.

Again, no evidance of any goop anywhere. This was on my 63 and the core I took out was dated 63.