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Heater Core Replacement - 65 RIV 401


dbaker9323

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Help!  My Mechanic tells me that my heater core on my 65 Riv (401) is totally blocked and needs to be replaced.  I have observed that the heater core encasement appears to be visible on the firewall;  the mechanic states it is not required to disssemble the dash board and go through the interior; rather it can be replaced from the engine side of the firewall.    Please advise.  

 

I would also like to know the best place to purchase a new heater core.  I have only been able to locate one online on ebay but thus far not directly from a distributor or manufactor.  Or is it necessary to have it recored?

 

 Thanks.

 

David Baker #14360

front dr quarter 65riv.JPG

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                              The factory intended for it to be serviced from inside the car but I wouldn't do it that way. People who have done it

claim that you can remove it from the engine side of the firewall if after removing the cover on the firewall if you take a cutting wheel

and enlarge the opening a little. I still have my original heater core and it is fine so far, but if it ever starts leaking I'm going to remove it

from under the hood. My plans are to take advantage of the situation if it occurs to detail the sides of my engine block and detail the oil pan,

(my engine has never been apart or removed from the car) so I will just yank the engine, put it on a stand and then I can go to town on the heater core from

under the hood very easily. It's way easier to R and R the engine than it is to tear the dash all apart. I could have the  engine out in an hour and a half. the worst thing about doing it from the inside of the car is that the defroster duct is made of a material that crumbles to dust

when you have to disturb it, then you have to spend hours and hours fabricating a new one. If I eventually have to change my heater core, I will document the procedure to remove it from under the hood....nobody has done this yet. Because of the aluminum timing cover and

thermostat housing and nightmare heater core job, it is imperative that you replace the coolant on these Rivieras every two years and don't

let the cooling system get low or lose it's anti-corrosive additives. this has been done on my car since it was new, and neither the radiator

or the heater core have ever been removed or leaked or gotten corroded or stopped up. It tells you to do this right in the service manual. The original owners of my car were dealership mechanics and they knew how important it was to maintain the coolant on these cars.

Edited by Seafoam65 (see edit history)
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Very difficult job. Most go through the console.  Your mechanic says it's blocked, but is it leaking? I had a bloccked heater core on a different vehicle once and the mechanic reversed the hoses and it flushed itself clean.  Might be worth a try. Easier to do toward the front other engine too. The hoses are different diameters so if I were you, I'd buy some extra hose and use some reducers to make it easier to deal with, no cutting or stretching of the good hoses.  Somewhere on this forum, there's info on filters you can put on radiator hoses.  If you can flush the heater core, you might be loosening up some junk that you need to trap before it gets into tne radiator.

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1 hour ago, Seafoam65 said:

 If I eventually have to change my heater core, I will document the procedure to remove it from under the hood....nobody has done this yet.

Winston,

Just thought I would mention it, the under the hood method has been documented, it is listed in the Technical Tips in the Members Only section of the ROA website.

 

David,

Since you are an ROA member you can go to the "Technical Tips" section of the ROA website and it gives details for the different methods to change the heater core. The following "Tips" are listed ...

 

2. '63-'65 Heater Core Replacement - Inside Method

3. '63-'65 Heater Core Replacement - Under Hood Method

4. '63-'65 Heater Core Replacement. GM Service Bulletin, May 21, 1965

 

I was thinking the under hood method had been posted on here at one time but I am not certain?

 

As far as buying one I believe your best bet is having yours recored? From what I have heard the replacements that are for sale don't fit, so a recore is the best way to go. Perhaps a more experienced member will comment about this?

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I dunno.  I replaced a leaking heater core a few years back (got the replacement from Advance Auto).  I don't remember it being a bad job at all -- but I can't remember if I went in from the inside or outside.  I think it was outside, because I do remember mucking about with the blower box for some reason.  I do not remember cutting the firewall, though.

 

If the core is plugged rather than leaking, you might take the earlier suggestion to flush it first.  Different vehicle, but I had a heater that was rapidly careening towards uselessness.  Disconnect both hoses, then repeatedly flush from both directions.  The first shot blew out a big belch of dark brown water, then subsequent squirts kept getting cleaner and cleaner.  10 minutes later, it was working like a champ.

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15 minutes ago, KongaMan said:

I dunno.  I replaced a leaking heater core a few years back (got the replacement from Advance Auto).  I don't remember it being a bad job at all -- but I can't remember if I went in from the inside or outside.  I think it was outside, because I do remember mucking about with the blower box for some reason.  I do not remember cutting the firewall, though.

 

If the core is plugged rather than leaking, you might take the earlier suggestion to flush it first.  Different vehicle, but I had a heater that was rapidly careening towards uselessness.  Disconnect both hoses, then repeatedly flush from both directions.  The first shot blew out a big belch of dark brown water, then subsequent squirts kept getting cleaner and cleaner.  10 minutes later, it was working like a champ.

An even better idea! Flushing it so that the water is not circulating through the block and radiator seems like a really good idea. ?

 

 

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2 hours ago, RivNut said:

Very difficult job. Most go through the console.  Your mechanic says it's blocked, but is it leaking? I had a bloccked heater core on a different vehicle once and the mechanic reversed the hoses and it flushed itself clean.  Might be worth a try. Easier to do toward the front other engine too. The hoses are different diameters so if I were you, I'd buy some extra hose and use some reducers to make it easier to deal with, no cutting or stretching of the good hoses.  Somewhere on this forum, there's info on filters you can put on radiator hoses.  If you can flush the heater core, you might be loosening up some junk that you need to trap before it gets into tne radiator.

 

Going thru the firewall is a lot easier ! Less chances of breaking a number of small parts . Call me anytime and I will walk you thru it . For a filter I use a kit made for Jaguar , google Jaguar coolant filter . It  is placed within the upper hose . Inside a cup is a screen and the cup has a screw on cap to clean the screen .

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11 hours ago, KongaMan said:

Disconnect both hoses, then repeatedly flush from both directions

I cleaned out the heater core on my 68 using this method after removing both hoses from the feed lines. I also lubed the heater core box controls where the control cable attaches on top of the firewall box controls because they were no longer functioning when I adjusted the temperature wheel on the controls. I am getting nice and hot air into the cabin now when needed. :)

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                         I agree with Mitch, at my shop most of the time we can unclog a clogged core by back flushing if we spend enough time

doing it. One problem I see though is it is very likely that once the crud is removed from the core, it is liable to start leaking. the fact that it is

plugged up indicates that the cooling system was neglected for a long time.

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9 hours ago, lrlforfun said:

OK Riviera People: I've disconnected the heater hoses from the core and blown it out with a pressure washer. Lots of black caca came  out. Worth a shot. Mitch

 

I considered using a pressure washer, but I decided it was too risky.  Specifically, repeated blasts of high pressure water might be a little too much for 50-year-old solder joints that have been vibrated for decades and potentially weakened.  Doesn't do you much good to turn a plugged core into a leaky core. ;)

 

I did come up with an "automatic" flush system, though.  Start with a small sump pump in a bucket of water.  Connect the outlet of the pump to the heater outlet hose.  Run the heater inlet hose back into the bucket.  You hook the hoses up this way to do a reverse flush rather than further compacting any blockages.  Turn on the pump and let it run.  The theory is that the constant flow of water will flush out all of the loose or lightly attached debris.  In practice, I'd probably blow the initial (dirtiest) waste water somewhere other than the bucket so that the debris doesn't get recycled through the pump and core.  You could also also put an inline filter (e.g. washer hose) on the line to trap any subsequent debris that breaks loose.

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First thing I ever did to mine was replace the core by taking the dash apart. Not fun but I've also done way harder modern cars where the core and the evaporator are in one unit.

 

Recently just got the car out of storage and a coolant flush along with a correct '63 heater valve were installed. So even though it doesn't have A/C, at least it won't fry my feet with vent air passing over the hot core.

 

 

Edited by jimtash (see edit history)
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What a great chance to develop a more casual acquaintance with your mechanic. Flush it out yourself first. It is messy, but will give you some intimate knowledge of the car and a bit of confidence.

 

If you can't unplug it I don't think you need much larger than a 1/2" socket and a couple of screwdrivers to change the core. It just takes patience and organization.

 

I am curious about the diagnosis. Did he disconnect the heater hoses and try to push water through? Seems like he would have said "When I didn't get flow I tried to backflush and couldn't force anything out." I did say that?

 

How would you like to go through a core replacement and find out the heater valve failed or a hose delaminated? Those are things that get you a phone call "I found something else." I am not a very trusting soul, but I was trained to be that way.

 

Are you in western New York? Maybe you just need someone to come over and sit on a bucket while you work. I point and grunt pretty good.

Bernie

Edited by 60FlatTop (see edit history)
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Hi David,

 

I did mine last year in my ‘63.

 

If they are the same as 65 then they are not difficult, but just time consuming. I took lots of photos along the way and had to clean and refurbish and renew bits as I found them, which consumes lots of time. (Just waiting for bits to arrive takes time)

 

I removed both seats and carpet and console, distributor and cover on the firewall. It is great practice for being a contortionist as some of the Fasteners are not easy to get to.

 

And if the floor pan is rusty, gives you an opportunity to clean it and repaint it and new sound deadening and underlay and ......

 

And I had a radiator guy repair and test my core which was plugged and leaking but was still a sound Harrison unit. That way I knew all my efforts would not have to be repeated if an inferior aftermarket replacement failed. Cos I don’t want to do it again,

 

Or you could take it to a Buick dealer as the repair time is only about 8 hours or so (ha ha)

 

The ROA gives details of both methods that you can print out. One is where you cut a bigger hole in the fire wall and pull it out that way or the traditional way is where you take out the console.

 

Because you end up removing lots of other bits to get to it, the job can seem quite daunting. But just do one thing everyday towards it and keep focused. 

 

Once you have done it you get a badge and tee shirt which says

 

”I removed and replaced the heater core in a first generation Riviera and survived (just) to tell the tale.”

 

??????????

 

 

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David,

 

   Remove the heater hose at the heater control valve going back to the heater core. Next, remove the heater hose from the water pump. MUCH easier to do it this way rather than trying to disconnect the hoses at the core. Someway, somehow connect your garden hose to the hose from the water pump. This will "Reverse" flush the heater core. DO NOT TURN THE HOSE ON FULL BLAST at 1st. Turn it on slowly so that if it is CLOGGED you will not over pressure it & CREATE a leaking heater core. After the water starts to come out clean you can increase the pressure as the core will no longer have a restriction. You can also try the correct routing, but it shouldn't change IF it was clear/clean. Then if you have a compressor or can borrow one give it a few blasts of air. Not real high pressure at 1st. Then increase pressure as it becomes more clean/clear. Then hook up the garden hose again & do it reverse flush again. The air will loosen up more debris & the reverse flush will get the rest out.

  I don't LIKE using a pressure washer because it can & sometimes causes an otherwise good/OK core to start leaking.

  Just my 2c worth.

 

 

Tom T.

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You can connect a garden hose to a heater hose using one of those hose repair kits with a barb on one end and a female hose connector on the other.  As a practical matter you don't have to go that far.  I used a cheap, small nozzle that I had around (about $2 at Home Depot)and just stuck it inside the hose.  Of course, that tends to be a bit messier. ;)

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If you own one of these cars long enough, you'll have a heater core story to tell.

 

I bought my '65 way back in 1983.  It was my daily driver for ten years.  For the first 5 years or so the heater worked just fine.  But then, gradually, it became less and less effective.  This was so gradual that I learned to live with it.  Oh, it was no fun on sub-zero days, waiting for some merciful heat to invade the cabin.  The only worse thing was a constantly fogged up rear window on damp cold days, as car does not have a rear defroster fan.  

 

Funny thing was, although my heater core was obviously plugged, it never leaked inside the car.  After I retired my Riv from daily service (I had a baby coming and was spending over $200 per month on gas in 1992) I didn't much worry about lack of heat as I used the car mostly during the warmer months.

 

Years later I undertook the restoration of my Riv.  It was time tor finally replace that darned heater core.  I did it as others here suggest - through the firewall.  You need to enlarge the hole in the firewall to get the darned thing out of there.  All this was made easier as I had the engine out to be rebuilt.  I used a pair of tin snips ("nibblers") to cut the firewall steel to enlarge the hole.  The cut areas aren't visible once you put everything back together, so no big deal.  

 

After I replaced the heater core I was amazed at the difference.  Now I can dry tobacco and roast chickens in there!

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If you want to make another beneficial change to your heater system, rewire the blower controls.  In the stock setup, the heater/defroster high setting is the same as the A/C medium setting.  Pop the controls out of the console, move a couple of wires around, and you can have full blow for your heater and defroster as well.  For more details.

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  • 4 years later...

This was a great thread about the woes of heater core replacement on first gen Rivieras.

 

I own a 64 Riviera and the previous owner disassembled the dash and removed the heater core.

 

He left it like that...

 

All the parts are in the trunk.

 

 

I think I have all the parts but not sure how they all go together.

 

There is a paper bag with some cardboard in it... he said that the ductwork got wet from the leak and came apart.

 

I was a member (expired now) of the ROA and tried to find pictures on the website but I had a hard time finding stuff and never found what I was hoping to find.

Rodney Beauchamp mentioned he replaced his and took lots of pictures and also that there are a ton of pictures in a document on the ROA website.  
 

Could anyone here help me get some documentation to ease the pain of getting the car back together?

 

Is the heater ducting that fell apart available?

 

Thanks guys!

 

 

 

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I don't know why everyone was saying it was so difficult to remove a heater core from a 1st gen Riviera unless the discussion is for A/C option models. I had a '63 with no A/C and from what I recall it was relatively easy to remove it from the engine side. There were just the hoses, some controls and the air box. I did back in the mid 90's. It didn't look like it had ever been replaced before. The opening in the firewall looked unaltered. The new one went back in with a little effort but nothing that stood out as particularly difficult. My local radiator shop even had one in stock. Maybe the early 1st gens were different? Mine was an early one sold originally in maybe Sept or Oct 1962. I'm still trying to find any of my old registration papers but I unfortunately purged a lot of my stuff when I made a big move in 1998.

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28 minutes ago, Bleach said:

I don't know why everyone was saying it was so difficult to remove a heater core from a 1st gen Riviera unless the discussion is for A/C option models.

I did it to my early '63 w/AC (Oct 1962) around 1990 when I had the engine out. Couldn't have been a big deal because I can't remember. I think I did it from the inside because the interior was torn apart.

I installed an original used heater core from a non AC 1963 parts car and is still in-service.

I do remember how satisfied I felt to have cleaned out all the gunk in the ducts.

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Question: historically heater core replacement is said to be one of the most difficult, time consuming Riviera repairs. If true, how come Bernie & Turbo knock the job out in minutes w pliers & a screwdriver, while everyone else struggles for days, dismantling dashes, breaking vital components, & cutting through firewalls w power tools? These men must either possess superhuman mechanical abilities or fading memories. I don't know whether to feel inspired or inadequate (leaning toward the latter).   

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One thing I haven't seen mentioned, if you go the filter route for your coolant system. You should check the filter at least every trip or when the car has been started for the first few times after the filter is installed and it should be removed for any long distance trips as the cooling systems for these engines is only okay and on the poor side for the 425's. Last thing you would want after that much work is burning up your engine due to a plugged filter. Also an old or new nylon sock would work just fine and they are very cheap and can just simply be thrown away and replaced with a new one at every check. You can place them on the upper radiator hose where the coolant flows into the radiator and would make checking it easy and convenient with minimal loss of coolant.

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Been there done that --1994--- did mine from  under hood ,, 1965   with   air con,  

all ok not a big job,  but i do remember that  the original was  a very tight fit, so  i went and purchased a  

mid seventies  Cadillac heater core from a wreaker, it was about  1/2 inch  smaller than the original,

had it checked  first, and rapped it in insulation, went straight in ,fitted very  easy.

To this day ,   still working great  for the new present  owner. 

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On 1/17/2022 at 2:19 PM, Tcox said:

This was a great thread about the woes of heater core replacement on first gen Rivieras.

 

I own a 64 Riviera and the previous owner disassembled the dash and removed the heater core.

 

He left it like that...

 

All the parts are in the trunk.

 

 

I think I have all the parts but not sure how they all go together.

 

There is a paper bag with some cardboard in it... he said that the ductwork got wet from the leak and came apart.

 

I was a member (expired now) of the ROA and tried to find pictures on the website but I had a hard time finding stuff and never found what I was hoping to find.

Rodney Beauchamp mentioned he replaced his and took lots of pictures and also that there are a ton of pictures in a document on the ROA website.  
 

Could anyone here help me get some documentation to ease the pain of getting the car back together?

 

Is the heater ducting that fell apart available?

 

Thanks guys!

 

 

 

If your referring to the a/c hoses that go to the eyeball vents, I sourced mine from Old Air Products in a length.

Rodney 😊😊😊😊😊😊

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  • 4 weeks later...
  • 6 months later...
On 1/16/2022 at 10:37 PM, XframeFX said:

I did it to my early '63 w/AC (Oct 1962) around 1990 when I had the engine out.

 

On 2/12/2022 at 10:20 PM, JMac1 said:

Heater cores for pre-1966 Rivieras are not available. They're recore-only.

AARG! On the drive home from a car meet yesterday August 27th, I raised the glass and turned the heater to full as it was cold even with my jacket. Then I smelled sweet antifreeze and the the door glass was condensating on the inside. Heater core from 1990 sprung a leak!

Replacement heater cores appear scarce.

I researched this forum and ROA website Tech articles which left me with a few questions:

 

1) Were there ever different heater cores between AC and non AC 1st Gen Rivs? If so, maybe they were different sizes?

2) If I have a choice, all aluminum, copper/brass or re-core? Which is preferred?

3) I've found 1 source. But, I prefer Canadian manufacturer Spectra Premium. However, they no longer do our application. Nothing on Rockauto either.

 

Thanks!

 

 

 

 

 

Edited by XframeFX (see edit history)
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IF the core in your vehicle is original have it re-cored. Cores are diff. between A/C & non A/C.

IF your core has been replaced with something unknown purchase a used core from a member parting a 1st. Gen. Riv. who knows the core they would sell you is an original.

 

Tom T.

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Aftermarket cores do not fit properly.

 

I got a used heater core from a parts car and had it recored.  Then when I had everything apart, the new core was on hand ready to be installed.

 

If you want to do that, you can have the old core that I took out of my 1963 Riv to have it recored.  Just pay postage to you.

 

I do not have a '65 Chassis Parts Book, but attached is a screen shot of the heater core part numbers for '63. They only list one number for the Riviera (4700), with or without A/C. The other full-size Buicks note with and without.

 

 

Screen Shot 2022-08-29 at 8.24.49 AM.png

Edited by Jim Cannon (see edit history)
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6 hours ago, telriv said:

IF the core in your vehicle is original have it re-cored. Cores are diff. between A/C & non A/C.

All I remember from 1990 is that it was good to clean crud  out during the replacement from the front. I did not examine the old AC core but I installed a used non AC heater core from a parts car that was cleaned and tested.

It was no big deal, meaning I don't remember having to cut anything.

 

A temporary bypass to see the end of cruising season and ultimately, a re-core it will be.

 

Thank-you All!

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Do you really need heat? If so, just bypass the heater core.  I had a car, can’t remember which one, that had a clogged heater core.  I little Korean mechanic, who knew tricks and short cuts for almost everything, fixed it by reversing the hoses and using the opposite flow to flush it out. After that we did a complete flush. I never had another problem.  I’m not suggesting anything, just relating a past experience.

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I replaced the heater core in my 64 non ac car in 2020. The replacment came from bestoffercounts.com. I had no trouble with the fit on the replacement. I did the removal and install from inside the car. I removed the seats for access (the passenger side carpet needed to be cleaned and dried also). The console can be moved back a few inches without disconnecting the heater control. I removed the plastic duct at the bottom of the steel heater core case to gain an additional inch. There was also a plastic cable stay that needed to be unfastened. The steel case was unbolted from under the hood and I was able to wiggle the whole thing out from under the dash. All and all it wasn't too bad, a lot of delicate brittle plastic. I don't know how much more trouble you would run into with ac if you have it. As far as the heater core itself is concerned, it has been installed for a couple of years now and I have no complaints. I checked his website and it still looks like they are available.

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