Upper Plenum Replacement

[JonJon68]

I've been closely watching a small upper plenum coolant leak for the last year in my 97 GP GT 3800 with 106,500 miles, no mods. So far it hasn't got any worse, however, I'm thinking about getting it repaired since I have the money now and for a peace of mind. Is there a new redesigned plenum for this car that will not warp or give me the same problem eventually? If so, about how much does it cost? I asked a service adviser at a local dealership and if I remember correctly he said the new redesigned part is around 300.00. If that's the case where can I purchase this part cheaper? Or another option is to just let them replace with the same plastic plenum since I don't think I'll have this car for another 100,000 miles. Thanks for any and all advise, this forum is "priceless"...

[richtazz]

You can buy an aftermarket one from Delphi or Dorman for $120-$150. They come with the upper plenum gasket and throttle body gasket too, so no other pieces are necessary. If you're handy with tools, you can do the job yourself. It's about an hour or so (maybe a little longer). Get a repair manual and follow the proceedure, making sure you torque everything down properly to spec. The Delphi part number is FH10095, and the Dorman one is 615-180, just for reference so some "parts monkey" doesn't get you a wrong part or tell you it's not available except at a dealer. These two numbers fit all vin-k 95-03 3800 series II. 95 was the last year of the vin-L 3800, so if someone else with a 95 reads this, verify which engine you have before purchasing (the 8th digit of your VIN number [L or K] will tell you which engine you have).

[JonJon68]

Thanks Rich. I do have a repair manual and this does look like a DIY job. Are there any more detailed write-up threads on here? I'm going to run a search. Also, I have never used a torque wrench and have been wanting to learn about these tools, is this a tool I can rent from Autozone?
Thanks again for the feedback.

[BNaylor]

Originally Posted by JonJon68

Also, I have never used a torque wrench and have been wanting to learn about these tools, is this a tool I can rent from Autozone?

Autozone rents torque wrenches. The one you will need is the one that reads in inch-lbs.

Very important that the upper intake manifold (UIM) 8mm bolts are torqued in sequence to 89 in-lbs. Fuel injectors rail bolt/nuts 89 in-lbs and throttle body bolt/nuts 89 in-lbs.

Like Rich said it is defintely a DIY job lasting only a few hours if you have all parts and tools needed beforehand. Of special note, the fuel injectors will be removed intact with the fuel injector rails and there is no need to disconnect the fuel lines from the rails. There should be plenty of write ups on the R&R procedure on AF. I have one in PDF file with illustrations.

[rbsteve]

GTP Dad wrote up a good one, which i followed to do the job just before xmas. use the search feature and look for "Upper intake" or "Plenum" You should find it.

I would buy new O-rings for the fuel injectors if you do this job. They are a breeze to install, and will avoid the possibility of any fuel leaks when everything is put back together. Im glad i did this to my car, while removing the old ones, some of them split in two. The rubber was cracked and deteriorated.

The whole job took me a few hours, but i went slowly to make sure i labeled all of the electrical connectors. Make sure you clean up the top of the intake. Any trace of old gasket or oil or coolant will produce a leak, since the new gasket will not sit properly.

You had best do this job, or have it done. Even though it looks like a small leak on the outside, inside the plenum it will be a real mess.

Good luck !

[StevePT]

Originally Posted by JonJon68

Thanks Rich. I do have a repair manual and this does look like a DIY job. Are there any more detailed write-up threads on here? I'm going to run a search. Also, I have never used a torque wrench and have been wanting to learn about these tools, is this a tool I can rent from Autozone?
Thanks again for the feedback.

I personally would buy your own torque wrench. You can figure the amount of money you save by doing your own work can justify spending ~$100 on a torque wrench.

I personally have Proto torque wrenches, but there's plenty of other torque wrenches that work well. For working on automotive stuff you'll want the click-type torque wrench as opposed to the beam-type. The clickers cost more, but are easier to use, work faster and smaller profile.