Plastic Coolant Bypass Fitting: *VIN-L 3800*

[HotZ28]

The heater bypass hose/fitting is located under the alternator and circulates coolant between the water pump and intake manifold. Attached to the intake, you will see a plastic fitting that has a hose barb on one end and threads on the other end, that screws into the intake manifold.

Usually, when the original plastic fitting becomes brittle, (5-10 years) the fitting may break, causing rapid loss of engine coolant. If the vehicle is moving at highway speeds when this happens, engine damage could soon occur from overheating.

We recommend anyone who owns any of the vehicles listed below, with a VIN-L engine and still has the “plastic fitting” installed, to upgrade to the steel one ASAP. If you don’t install this hose/fitting, at least buy them and keep them handy in case of a failure.

The metal hose fitting, can be found at most national part stores in several brands, like Dorman, Help, or Motormite and comes with 5/8" hose x 1"-14 thread. All three of these aftermarket fittings use the same Part #56359 and are available for less than 5 bucks. Of course, if you prefer, most GM dealers would have a replacement metal fitting, Part #25535749 for 15-18 bucks. Keep in mind; this fitting is only for the VIN-L 3800 engine and not for the 96 up VIN-K 3800 Series II. The VIN-L engine came installed in Buick, Olds and Pontiac, in various body platforms.

For removal of the fitting, (if you don’t have a large thread extractor), you can use a flat chisel about the same size as the I.D. of the hose nipple. The cutting end of the chisel is tapered and should go up into the threaded piece about 1/2 in. You will need to bump it in with a hammer far enough, to get a grip on the fitting. Once the chisel is snug, use a crescent wrench to turn the chisel “counterclockwise” and that will loosen the fitting. (It should start coming out). If the chisel slips on the first try, tap it in a little further, then try again.

In addition, you have several options for the bypass hose; Goodyear Part # 63043, Kelly Springfield Part # S-3041, DAYCO Part # 71624, GATES Part # 18801 {5/8" x 7 1/2" Cut to fit) Price range on the bypass hose ranges between 6 and 15 bucks, depending on brand selected. Replacing the hose clamps is optional, if not damaged.


Buick Vehicles that may be affected:

1990 - 1995 Regal

1992 - 1995 LeSabre

1991 - 1995 Park Avenue

1991 - 1995 Riviera

1991 - Reatta


Fitting:


Hose:

[Scrapper]

thats the tube i was telling you about there bad on leaking alltho my dads 91 pa never to leak until 5 years later.

[ctwright]

I just want to second the post here, very useful information for anyone with that engine, don't wait until it's too late.

I have a 93 regal, and I didn't know that it had any fittings like that made out of plastic type material. So it was too late for me, it cracked on mine, and I didn't have any way to get it out. I tried everything, I took a tiny saw blade and made a notch or to where it was threaded in to the intake, I managed to find something to fit in there and turn a little bit of it out, took a pocket knife tried to get the rest out, no luck. Then had to take a torch to it and heat it, kept working with it and working with it with the pocket knife, got more out a little at a time, never wound up getting all of it out but enough to where I could get the new steel fitting on there. I couldn't tighten the new one all the way down where the rubber seal goes against the intake, still had like a quarter inch to go. However I guess it was good enough because I still have the buick almost two years later doesn't leak from their any.

Please take that info seriously because it was a pain in the neck trying to get the old broke off fitting out of their, and I still didn't even get it all out.

[SLCLandShark]

I found this thread extremely helpful! Wanted to add a couple things..

My 95' Coolant Nipple was so eroded that it pretty much crumbled when touched. I had been seeing coolant leak (on and off) for a couple days sometimes more then others. (My car had already had a new water pump replaced. I took it to my mechanic friend and he accidentally discovered the fragile nipple break down. it was easy enough to loosen the belt & move the alternator aside to access the area. we initially had a difficult time removing the old brittle threads that were still inside the lower intake manifold from the nipple. So we took a trip to our local hardware store and purchased the $5.00 Sprinkler system "Nipple Extractor Tool". after getting it to fit snug (used a hammer a little) inside the old threads twisting the tool Counterclockwise they came loose! Purchased the new part from a GM dealership (was nearby) cost was $28.00 (Whoa!) but it's a heavy duty metal one with the "o-ring" ready to install. Hope my 2 cents helps!