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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Hey guys I recently got an '88 firebird GTA and I noticed one of the holes in the valve cover on the driver's side had a broken rubber grommet (which I removed) but no hoses or anything attached to it. In other images I have seen it looks like it goes to the engine somewhere but I've looked and can't seem to find where it might go. Does anyone know what it is and where it goes?
I don't think it's the PCV valve and it's not the oil fill. I heard it could be a "breather" but I'm really not sure.
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Thanks for the response! I located my PCV but it is on the passenger side valve cover. Are you saying there is another one on the driver's side or is the passenger side not the PVC? There are three holes in the valve covers: one on the passenger side (PCV?) and two on the drivers side (one is the oil fill but the other I am unclear about). That is the one I am asking about. Thanks
On these TBI/TPI engines there is an oil fill opening, PCV valve and CC breather grommets in the valve covers.
Your 1988 TPI engine had the PCV valve at the front of the driver side valve cover and oil fill at the rear of the driver side valve cover. The Crank Case breather vent was at the rear of the passenger side valve cover. 1990 and up TPI engines had the oil fill at the front and the PCV valve at the rear of the driver side valve cover and passenger side had the CC breather vent moved to the front of the valve cover.
You car has a GM crate engine replacement as indicated by the sticker on the side of the driver side vale cover. IDK which engine it is because I can't see all of the sticker. You need to get a 1990 and up style TPI PCV molded hose to swap for the 1989 and down style hose.
Last edited by Airwolfe; 09-10-2024 at 11:50 AM.
Reason: Edited because I had made a mistake.
Someone has installed the brake booster hose where the pcv hose is supposed to be.
remove the booster hose from intake and put it in the rear driverside of the plenum where its supposed to be.
Ok thank you all so much for your help. I will move the power brake vacuum line to the back of the plenum (which currently has a rubber cap on it) and get a PCV valve to connect to where the PB hose was. I will also replace the old 1988 PCV valve with a valve for the 90s engine.
I edited my reply I posted earlier because I realized I had made a mistake.
I worked on a 1989 and a 1991 GTA today with the Tuned Port Injection engine.
The 1988 to 1989 has the PCV valve at the front of the driver side valve cover and the oil fill at the rear. The passenger side valve cover has the Crankcase Breather Vent at the rear of the valve cover.
The 1990 to 1992 has the oil fill at the front of the driver side valve cover and the PCV valve at the rear. The passenger side valve cover has the Crankcase Breather Vent at the front of the valve cover.
Thanks yall this was very helpful. The way I understand it for the 88 gta, the pcv valve goes on the rear of the driver's side valve cover which goes to the engine (vacuum?). Then the passenger side hole (intake) just should have an elbow leading into the intake manifold. I guess the layout changed a lot over time.
Passenger side valve cover should NOT go to the intake manifold; should go to the passenger side of the TPI throttle body as it provides a filtered air source for flow into the crankcase that is then sucked into the intake manifold though the PCV valve (when opened by positive crankcase pressure).
The pcv valve goes on the on the vacuum (driver's) side not the intake (passenger) side right? One side has an elbow and the other has the pcv valve but from my research I keep getting different answers.
The pcv valve goes on the on the vacuum (driver's) side not the intake (passenger) side right? One side has an elbow and the other has the pcv valve but from my research I keep getting different answers.
Note: I'm not going to be mentioning the 1985/1986 or 1987 style valve covers or filtered fresh air Crankcase Ventilation system or Positive Crankcase Ventilation system.
Your car is a 1988 GTA but your engine is not the original 1988 GTA LB9 or L98 TPI engine. It is a replacement GM crate engine and which one is unknown to me because I can't read the label on the driver side valve cover and I don't know what numbers are stamped on the engine.
The driver side valve cover on the replacement GM crate engine is the same layout as a 1990 to 1992 LB9 or L98 engine.
The passenger side valve cover I can't see because you didn't provide a picture of it. If it has a small hole for a press in grommet at the rear of the valve cover it is a 1988 to 1989 passenger side style valve cover. If it has a small hole for a press in grommet at the front of the valve cover it has a 1990 to 1992 passenger side style valve cover.
Your PCV connects to the vacuum fitting under the fuel rail next to the injector for cylinder number 5. Pay no attention to the stuff at the top left of this picture. This picture is just one I found online to show you where the PCV hose, valve, and vacuum port are located and routed.
The PCV valve you need is Genuine GM OEM part number 8995284 or AC / ACDelco CV-789-C.
Here are more pictures of how I have it set up. Thanks for all the help.
Drivers side PCV Passenger side hose connected to throttle body Passenger side Drivers side pcv sticker on driver's side valve cover (does this mean it is not the original 350 engine?)
Do I need to replace the PCV and grommets? Right now i just have a rubber elbow in the passenger side grommet, should I get the fresh air ventilation hose?
Does the pcv valve change on a crate engine or is it just the fit?
Your 1988 GTA either has a replacement GM Goodwrench New 350 crate engine or it has the driver side and passenger side valve covers off a GM Goodwrench New 350 crate engine. I can't imagine why someone would replace the factory valve covers on your original L98 engine with the valve covers off a later model GM Goodwrench New 350 crate engine. So odds are good your GTA doesn't have its original L98 engine anymore. I don't know which GM Goodwrench New 350 crate engine you have without seeing the part number or other numbers stamped on it. It could be a L05 5.7L TBI flat tappet cam truck engine, a L05 5.7L TBI roller tappet cam engine from a passenger car like a Chevy Caprice or Buick Roadmaster, or it could be a L98 5.7L TPI roller tappet cam engine from a Camaro or Firebird. It could also be some other 5.7L GM Goodwrench New 350 crate engine.
This GM Goodwrench New 350 engine has the same driver and passenger side valve covers as a 1990 to 1992 LB9 & L98 TPI engine in a 3rd gen F body. So you will need to use the passenger side Crankcase Vent and driver side Positive Crankcase Ventilation system as setup on a 1990/1992 TPI engine. This appears to be how you have it setup up now except on the passenger side the Crankcase Vent hose goes to the top port on the throttle body and not the one you have it on now. Right offhand I don't remember what goes to the port you have it connected to now. I'll have to look at a car and see.
The grommets, elbow, hoses, and PCV valve seem to be OK as you have them now except that one on the passenger side needs to be relocated to the proper port on the throttle body. PCV valves are calibrated to the engine they are used on based on several factors. Compression ratio, camshaft, engine vacuum at idle and other things. If the engine is idling smooth and the oil is staying clean and not sludging up and there aren't other drivability problems that can be caused by the PCV system then the PCV valve you are using is probably OK.
I wrote to the guy I bought it from and he says it is the original engine, just rebuilt. What does this mean for the pcv or other systems? Is it possible that the valve covers were just replace but not the engine itself?
I can't for any reason think of why someone would rebuild an engine and replace the factory original GM valve covers with the factory original GM valve covers from a brand new GM Goodwrench crate engine. Valve covers aren't something that wear out.
The most logical explanation is your GTA at some point in time had a brand new GM Goodwrench 350 crate engine installed in it.
Nothing needs to be done with the PCV system. The hoses run to the same place on the lower intake manifold and the throttle body no matter if it is the 1988/1989 style valve covers or the 1990/1992 style valve covers and the grommets and PCV valve are the same. Your engine has 1990/1992 style valve covers and you have the hoses routed for the 1990/1992 style vales covers. Assuming you route the passenger side hose to the top port on the throttle body.
Yeah that seemed weird to me as well but the engine seems to run ok. I'll move the pass side hose and cap the other one.
I looked and I found the engine date marked on the to be A058 which I think means January 5th 1988 or 1998. Does this mean anything to anyone about what the engine could be. I did some research and did confirm it is still a tpi engine which I think means it could either be the original 88 engine with a few replaced parts (explaining the sticker) or a 1998 L98 crate engine compatible with the 88 but with the 90-92 pcv system.
09-01-2024, 03:11 PM
