Intercooler Hoses - Why they matter in restoration work


Bad luck Buick
Jun 16, 2014
Hello all. RC and I have been working a few cars where the directive from the customer is to "present the car in factory or showroom condition." As you all know Richard (and now I for that matter) can be very picky when it comes to original parts. So when a customer had supplied us with aftermarket restoration hoses and hose clamps for his otherwise perfectly stock car we decided to create a document demonstrating the differences between original, aftermarket, and even oem replacement hoses. These are the details that when attended to really leave an impression on us when judging factory original cars. We hope you all find this informative and useful when restoring your car or making a decision to purchase one.

The following is direct from Richard Clark:

Here is a bit of info on the TR intercooler hoses that might interest those that are taking restoration seriously. As us old timers remember one of the first things that caused us trouble when we started turning up the boost on our cars was the frightful experience of having one or more of the intercooler hoses pop off. This was usually accompanied with an extremely loud pop and the sickening feeling that we had surely just blown up our engine.

Had we left the boost alone and kept things at the meager 12 lbs set at the factory (15 on the GNX) we would not likely have seen quite as much of this problem. Fact was that the original hoses were generally adequate if the car was left as it was built. The original hoses were made by a Michigan company Flexfab and had a wall thickness of 0.1 inch. The hoses came in three lengths and diameters. The hose on the turbo outlet (part # 25525234) was 2.4 inches long and had an ID of 2.0 inches. The hose on the intercooler outlet (part # 25525232) was 2.6 inches long and had an ID of 2.5 inches. The hose on the throttle inlet ( part # 25525233) was 2.0 inches long and had a ID of 2.6 inches long. All of these hoses had a total wall thickness of 0.1 inch and had a inner orange silicone liner covered with a black rubber wrap.

As with nearly all under hood rubber items on the car, these hoses were date coded. The white printing on them indicated the date of manufacture as to quarter and year. For example 4Q87 meant fourth quarter of 1987.

As nearly everyone will agree probably 98% of these cars got rubber coupler upgrades decades ago for good reason. When the hoses got hot they got soft and when they got an oil film on them they could slip out of position very easily. Early on many vendors offered longer and thicker hoses along with upgraded clamps. With performance upgrades these items are an absolute must and any attempt to skip their addition to your car will be met with lots of frustration.

That said, there is still valid justification to retain the original hoses and clamps in certain cases. If the owners intention is to keep the car in original condition and looking stock for car shows or for investment purposes retention of the original hoses and clamps is a definite must. When the hood is opened the clamps and hoses are right at front and center and are one of the first things that you see. Problem is few owners and even some car show judges even know what original is. That is the purpose of this writing to clarify in detail just what original really was.


Picture 1 shows three sets of “correct” Flexfab hoses. To the left is shown an original set as shipped on the car. In the center Is a set of Flexfab hoses without original GM numbers and with date codes that are after 1987. At the right is a set of Flexfab hoses with thicker walls and longer lengths than the originals as sold by some vendors.


Picture 2 shows the same hoses with the lettering and date codes showing. Of course most of the time the hoses were turned in a manner that obscured the lettering unless the clamps were removed.



Figures 3&4 show that different type styles were used throughout the years and even within the 86/87 model year there were differences.

As for original clamps the brand name was TRIDON and was clearly stamped on the clamp along with the metric size and the origin Canada. The clamps came in three sizes and were clearly stamped. The turbo outlet was marked 032. The up pipe had 040 and the turbo inlet, mass air and elbow were 048. They were marked stainless and unlike common perception they were not actually black but had a very dark brown/black hue. Even from GM replacement clamps did not match the production originals. Replacements had thread cuts that allowed a larger range of size.
Both of my my cars have their original hoses and clamps. I also have a couple complete NOS sets that have the white lettering on them.
Great info. Xavier. I'm not in the resto crowd but it is great seeing you document this type detail!

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Great to know! Now what I would really like to see .... a complete restoration guide on the 86/87 Turbo Buicks. Now that they are being restored in greater numbers & many more will be with time! Something like the Corvette or Mopar restoration guides that are out there. I'm sure there is a person or two in the Buick community with this knowledge & it would be great of them to pass-on with some sort of book!