Dec. of '09 I got good info from members on how to change out and make repairs to water leaking from my GP. The video that was available showed repairs being made to a Supercharged engine. I'm faced with doing this work over completely as the instructions that came with the new plastic upper plenum state, "if the pcv tubing is not installed correctly, the hot gases from the EGR valve will eventually burn the plenum and may cause extensive engine damage. I'm afraid that is where I made my mistake when doing the first repair. Hopefully, someone will help me to avoid this again. The new plenum has a black plastic tube that to all indications, remains in the upper plenum. There are a few short steel tubes that may need installed into the lower intake manifold and when installed, will stick up and protrude into the bottom of the lower plenum. The first time I did this repair, I did not touch that steel tube that is in the lower intake, which seems to be in there pretty solid. I would like to discuss this with someone who has had experience with this repair as I really do not want to make a second mistake.

Thanks,
Walt

412-584-9200

Hey there Walt,

This place sells the updated upper plenum with the steel sleeve & smaller EGR Tube: GM Intake "Sure Fix" Manifold Kit

Install guide can be found here: GM Intake Manifold Kit - Installation for 17806

The upper plenum gasket has guides to help hold the PCV Valve tube into place; the slightly curved end fits into a hole in the plenum under the PCV Valve, as seen here:



At some point I'll need to get a couple of these upper plenums, so I can't really comment further on them, but I hope this helps!

Yup, that there is the culprit! They keep a crackin and water keeps flowin. I finally finished the re-do about 3 days ago. Now have a new problem. The car was driven much too often with the upper plenum leaking and temps being elevated, although, there was never any indication the crankcase was contaminated as the so called milk shake appearance. So, I put off the re-do until I could get all the parts needed. Back to the new trouble. Cylinders # 3 and # 5 are not firing normally and the code indicates cylinder contamination. Did a compression test today and all cylinders show 150-155 psi except # 6 which shows 170 psi and # 3 shows 70 psi and # 5 shows 105 psi. These pressures are both dry and wet testing. IMO, I'm hoping the valve springs to # 3 and # 5 are so contaminated with hardened oil that this is the reason for poor compression and firing. I'm going to pull the valve cover Sunday and do a thorough inspection and go from there. If spring action is normal, then, next step is to pull the head and do what ever is needed. Should I be concerned with the compression reading of 170 psi on cylinder #6 or is that close enough to the 10 % plus or minus. Then again, I do not know what normal compression is on a fairly new engine? It's true what is said about these 3800 engines, they are bullet proof as this one has 228,000 miles logged and before this latest trouble, still ran pretty damned strong.

If anyone has had experience as this, please chime in if my solution to resolve is not the right one.


Walt

well being tht you have changed the intake all ready i was gonna add that the two silver "tubes" in the above pic are what shold be put in the lower intake before you put the upper intake on . just one of them.. the one that is the original needs to come out. it is too big and makes contact with the intake and causes warpage that leads to leaks. the smaller diamiter fo the included tube prevents this by not haveing the heat transfer.

as for you cylender pressures the only thing that really concerns me is the 70 psi.. that is a bit low.. the 105 is low but not as troubling as the 70. it could be several items cousing it. from rings going bad to valve sticking, to gasket to bad valve seat to chipped/broken piston, ect. ect. there are several items. you could try playing with the valves a bit or pull the head and see if there is another reason. after that i would unfortunaly say time to freshen up the ol' girl. or swap it out.

_________________

2001 white gt coupe with enough crap to make it run mid 13's with 3 bad pistons
2002 40th GTP sedan mostly stock

Thanks for the input. I did change out the old tubing to the correct new one. Looks like I have no choice but to tear it down again. I'll try your suggestion and see if a few valve springs are hanging up. Removing valve covers on these animals is no easy task either. If not, off comes her head. Just when you think you're outta the woods!?

About to get serious again. I ordered a new GM Headset and OEM valve seals and we plan to get started this weekend to remove the front cylinder head. Need some advice on a few thiings. First, just to make sure, the cylinder heads I believe are cast iron? Please correct me if I'm wrong and if they are aluminum? Second, I know for a fact, when changing head gaskets on my '87 GN, I have got to install new head bolts, as they are a one time use only. Does the same apply on the '99 GP 3800? Can the head bolts be used over, or is it wise to get new bolts? I plan to make a holder and keep the rockers, lifters, push rods, valves, etc. in their proper place on the cylinder head; whereever the parts came off, they will go back in the same slot. I plan to take the head to Pittsburgh Crankshaft and have them magnaflux and if needed, shave the head.
How many thousands can safely be removed before it becomes an issue with the lower intake manifold? For the moment, I do not plan to remove the rear cylinder head since the compression #'s were quite good. I believe, "if it ani't broke, don't fix it".

Any help to my questions greatly appreciated.

Thanks,
Walt

The heads are cast Iron, yes, and the headbolts are TTY so they are 1-time use only. ARP is the only company that makes reusable headstuds that I can think of.

Why not just change the other gasket and get the headwork done now while it's torn apart instead of having to do it all over again later on?

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'05 WRX STi - COBB Stage 2|Invidia DP|3" Borla XR-1|Coilovers|Camber Plates|Swaybars|Endlinks|Bushings|Braces|Anti Lift Kit|DBA4000s|SS lines|
Sold: 06 Cobalt SS/SC, 99 GTP 245WHP/326 Ft-lbs, 06 R6

Thanks for the info. Just got back from local Meineke shop and had new oem transmission lines installed. That takes care of the fluid leak at the radiator. While car was up in air I got a good look at underside and I was about to barf. Brake and fuel lines near fuel filter need replaced. There is an exhaust fitting on passenger side that comes right off the exh manifold that broke or cracked and needs replaced. Now, to the big stuff: both rear strut springs are cracked and the unibody sheet metal at top of the struts is rotted out and could be anytime the strut could poke through to the trunk.

I think I'm gonna do a coin toss to see whether or not I do the engine repair or just wing it till car self destructs? I figure, with the repairs I mentioned, could cost me up to 3 grand. Don't know if this is all worth it or not?


purely and totally ed,

Walt


Here is a list of parts I installed in the last several weeks:

1. New rad.
2. New trans lines.
3. New plugs, wires, coil packs, ignition module, water level sensor.
4. New water pump.
5. New power steer pump.
6. New upper plenum, lower intake gaskets.
7. New MAP sensor.
8. New tires.
9. All new rotors.
10. All new brake pads; ceramic.

Everything you mentioned would be easy to take care of except the strut tower rot. That's what lead me to sell my GTP

good luck and let us know what you decide. FWIW the strut towers were really bad on my car, one side has a hole about an inch in diameter (or it did last august, who knows how big it is now). They were rusty when i first got the car though, so they could have been bad for years and the car is still on the road today.

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'05 WRX STi - COBB Stage 2|Invidia DP|3" Borla XR-1|Coilovers|Camber Plates|Swaybars|Endlinks|Bushings|Braces|Anti Lift Kit|DBA4000s|SS lines|
Sold: 06 Cobalt SS/SC, 99 GTP 245WHP/326 Ft-lbs, 06 R6