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1968 Riviera Radiator Overflow Tank Kit 981766 Installation


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Recently I purchased a NOS 1968 Buick Overflow Tank Kit on Ebay. (part number 981766). This kit appears to be specific to the 1968 model year according to the online Buick parts references I use. 

NOTE: The directions for this kit don't provide any recommended routing suggestions for the overflow tubing. It's up to you to decide where to route the tubing.

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I chose to install the reservoir tank on the driver side inner fender due to the AC hoses and assembly on the passenger side fender. 

Below is the tank and wire cage assembly being test fitted. 

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I used the top forward dimple in the inner fender to locate the right bracket screw. The kit instructions say to drill 5/32nds pilot holes for the bracket screws. I placed a bit of electrical tape over the screw holes to keep the bracket from scratching the fender. 

I bent the bracket arms back on themselves to get the tank mounting angle I wanted then I screwed the bracket arms onto the inner fender. 

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Small washers were put behind the screw heads in order to provide even screw pressure on the bracket arms.

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The under-hood clearance of the tank and bracket is checked. 

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I bought 8' of 3/8th inch fuel line for this project. The overflow hose runs from the top nipple of the bottle, past the headlight control diaphragm, and down through the round hole at the bottom of the fender cavity bracket. 

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I put a strip of electrical tape on the raw edge of the inner fender support opening...

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and a 1/2" hole liner in the cavity hole to help prevent chaffing of the hose. 

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I decided to route the new overflow hose across the top of radiator support cover. The kit includes aluminum hose clamps and chromed sheet metal screws. I decided to use black plastic hose clamps and black self-tapping screws instead. 

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The radiator to tank overflow hose is secured on both ends with yellow hose clamps supplied in the kit. 

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The kit includes a 14 pound replacement radiator cap and a decal for correctly aligning the cap to the radiator overflow hose.  

This cap replaces the stock 15 pound radiator cap normally installed on the 1968 430 radiator.

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Radiator cap decal aligned with over flow hose and applied to radiator cap.

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The finished product. 

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In the near future I may buy more tubing and route it under the radiator to the overflow tank for a less cluttered look.

Edited by NC1968Riviera (see edit history)
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  • 1 month later...

I took The Aqua Zephyr out for a run today at my wife's suggestion when she wanted to visit a friend of hers. It was the first time driving the AZ since installing the radiator overflow bottle kit a few weeks ago. 

As can be seen below, the system works! The radiator overflow was captured in the bottle instead of draining down the overflow hose and all over my engine compartment! Hallelujah! 

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12 minutes ago, Rivdrivn said:

Mine has been there since the original owner had it installed in the ‘70s. It gets hot here in Florida and he used to pull a boat.

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I would be interested in seeing how your overflow hose is routed from the radiator to the bottle. 

My over the top of the radiator routing works but it's not very attractive. 

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Mike, I just noticed that the AZ has the extremely rare and sought-after 'BA' engine option!  That probably explains the extra heat.  (Or perhaps it's just a Bad Attitude that explains the urge to spit on the ground...).  ;)

 

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On ‎12‎/‎29‎/‎2019 at 9:06 AM, EmTee said:

Mike, I just noticed that the AZ has the extremely rare and sought-after 'BA' engine option!  That probably explains the extra heat.  (Or perhaps it's just a Bad Attitude that explains the urge to spit on the ground...).  ;)

Ha! Good one. The kids always get a kick out of that sticker! 

Edited by NC1968Riviera (see edit history)
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  • 2 weeks later...

Correct me if I am wrong but that has to be one of the most obscure options ever to be found for 1968. To my knowledge overflow bottles didn't become a thing until 1970. I have 2 69 Buick's that are pretty correct cars and I've also studied a lot of Engine Compartment pictures to get mine correct.  I also have a 1970 full sized Buick that did have a recovery tank (i'll call it) It was much bigger not rounded by any means and located on the right front inner fender be hind the battery. So the hose from the radiator is pretty short and didn't have to be routed any particular place. I've seen this configuration on many 1970 Buick's mostly full sized but also some A bodies. This is a first for me seeing an over flow for pre 1970.

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4 minutes ago, mstapell said:

This is a first for me seeing an over flow for pre 1970

Thanks for sharing your experiences with us!

 

If you look at the Buick Parts manuals, part number 981766 appears to be specific to the 1968 model year only. As I stated above, the instructions with this kit don't include any directions on where to place this kit on US built Buicks. It does show where to place the overflow tank in an OPEL and how to modify the radiator cap opening to accommodate the new 14# radiator cap.

 

I feel very lucky that the hose nipples on the plastic bottle are not brittle after 50+ years of storage. The system seems to work as it was intended as hot fluid fills the overflow tank then the radiator sucks it back in as the system cools.

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Mike,

My question is this. Do you need the overflow tank because your engine was overheating or is the overflow tank just something that could be added?

 

 

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Just now, RivNut said:

Mike,

My question is this. Do you need the overflow tank because your engine was overheating or is the overflow tank just something that could be added?

My engine is not overheating (according to the temp gauge) but if you fill the radiator up to 1" from the cap opening, the radiator will spit a lot of it back out after it comes up to operating temperature.

The coolant level would then be about 6" below the cap opening but the engine would not appear to be overheating at all.

I could continue to run with the coolant at this 6" low level but I'd rather try to keep the radiator as full as possible.

I am tired of cleaning up the mess it makes every time this happens. I would not have added this NOS overflow tank if this didn't keep happening.

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1 minute ago, mstapell said:

Lots of points can be lost under the hood.

So I hear. I have not had the car judged for originality yet. I guess I might have to bring my 1968 parts manual if I ever do!

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An original radiator has a cold fill stamp level about 5 inches below the full neck.

This space is allotted for the thermal expansion of the coolant.

The bottles were added later once the environmentalists caught the overfilled poison being dumped on the public roads.

 

 

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An original radiator has a cold fill stamp level about 5 inches below the full neck.

This space is allotted for the thermal expansion of the coolant.

The bottles were added later once the environmentalists caught the overfilled poison being dumped on the public roads.

Thanks for pointing that out!

I think my radiator is original to the car. 

That would explain why it keeps spitting coolant out! 🤷‍♂️

Edited by NC1968Riviera (see edit history)
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When is the last time you flushed your cooling system?  Could be clogged a little or your cap might not hold the pressure it was designed for.  Parts, just like us, wear out with age.  

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3 minutes ago, RivNut said:

When is the last time you flushed your cooling system?  Could be clogged a little or your cap might not hold the pressure it was designed for.  Parts, just like us, wear out with age.  

I flushed the radiator and heater core when I installed a new thermostat, hoses and hot water valve two years ago.

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Next time you get a chance, pressure test your old radiator cap.   Could be that it just didn't  have the strength to hold back normal pressure.

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Mike, 
I know that you're a '68 Riviera purist but I think that you (and others) might get a kick out of watching this video.

 

If I hijacked this thread, let me know and I'll move it or delete it.

Edited by RivNut (see edit history)
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  It`s normal for coolant expansion to occur in any car. The reason the OEM`s went to an overflow system is to make it possible for owners/mechanics to check the level of the coolant at a glance instead of possibly opening the radiator cap while under pressure. I have seen techs who should or do know better, do this with disastrous results. This benefit only exists if the overflow system is operating as intended so I always still check the coolant level in the radiator when servicing a vehicle.

  An ancillary benefit to adding the reservoir is doing so also adds a little additional capacity to the cooling system. Unfortunately, that extra capacity only exists while the cooling system is not up to operating temperature so in effect it doesnt add much of an advantage to cooling the engine.

Tom M

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