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99 GM 3.1 V6 whistle after intake manifold gasket replace
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DanK1966
New User
Mar 9, 2015, 3:01 PM
Post #1 of 10
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99 GM 3.1 V6 whistle after intake manifold gasket replace
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Hi, I've got a 1999 olds cutlass with 3.1 v6 vin J.
Due to P0107 and failing emissions test and disappearing coolant, along with hydrocarbons in coolant, I replaced upper and lower intake manifold gaskets. (oil was fine though, no water in it).
I just got done installing the new intake manifold gaskets. When I pulled the injectors/fuel rail, I had to lightly pry it them out as many people recommended. When I put the injectors /fuel rail back in, I pressed them all down until the bracket that holds the bolt into the manifold was flush with the mounting tab. I removed them again and they just slip right out easily. Should I be expecting them to need to be pried out again?
The reason I'm asking is that there's now a loud, multi-tone vacuum whistle when it's at part throttle, and it's idling rough like it's got a vacuum leak. When I idle it and spray carb cleaner in the area under the top manifold, right near the injectors, the engine idles smooth and revs right up like 1 or 2krpm and begins it's whistiing until it's sucked in all the carb cleaner. In that area, I'm thinking that it must be either the injectors or the gasket upper->lower manifold.
I took off the upper again and replaced the injector o-rings and studied the injectors install postiion. It appears there are machined seats for each injector in the manifold kind of like what a spark plug seats in for the injectors, although the bottoms of the injectors are not flanged to contact the entire seat, but the bottom of the matching wide body on the injector never gets within say 1/8 of an inch away from the flange. The o-ring goes pretty far in so I cant see it anymore and the rail brackets set easily on the bracket screw stud. Is there more to it or are the injectors just fine? I didn't remove any injectors from the rails or dissasemble the rails/injectors in any way other than to replace the injector o-rings. I've done a few rebuilds on 70s small block chevys with never any problems to speak of, but this 60degree v6 seems such a piece of mal-engineered tempermental junk, and it's all new to me so theres so much to learn. My first time dealing with injectors as well. Any help appreciated.
Also, the whistle doesnt go away when I remove the oil cap. It just idles rougher.
Dan K
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Hammer Time
Ultimate Carjunky
/ Moderator
Mar 9, 2015, 3:24 PM
Post #2 of 10
(1942 views)
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Re: 99 GM 3.1 V6 whistle after intake manifold gasket replace
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Let me ask you ask question.............
How do you suppose that combustion gases got into the cooling system through an intake gasket?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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DanK1966
New User
Mar 9, 2015, 3:39 PM
Post #3 of 10
(1936 views)
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Re: 99 GM 3.1 V6 whistle after intake manifold gasket replace
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Hydrocarbons blow past piston rings into the crank case. The crank case gases are rerouted through the PCV valve into the intake manifold.
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Hammer Time
Ultimate Carjunky
/ Moderator
Mar 9, 2015, 3:48 PM
Post #4 of 10
(1933 views)
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Re: 99 GM 3.1 V6 whistle after intake manifold gasket replace
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And you think replacing the intake gasket is going to fix that?
The engine has a blown head gasket. They are notorious for that.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
Ultimate Carjunky
/ Moderator
Mar 9, 2015, 5:13 PM
Post #5 of 10
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Re: 99 GM 3.1 V6 whistle after intake manifold gasket replace
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Looks like someone is going to be tearing it back apart.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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DanK1966
New User
Mar 10, 2015, 9:57 AM
Post #6 of 10
(1912 views)
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Re: 99 GM 3.1 V6 whistle after intake manifold gasket replace
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Actually it sounds like you have no experience with 60degree v6. They are not notorious for blown head gaskets. They are notorious for hydrocarbons in coolant resulting from leaky intake manifold gasket. The original gasket was plastic and it heats up and cracks and leaks in many ways. Just google "plastic 3.1" and you'll see.
As far as my original post. I didn't say Exhaust in coolant, I said Hydrocarbons. Hydrocarbons do appear in non ZEV cars, because they are almost never fully burnt. Gasoline is almost pure hydrocarbons. So yes Hydrocarbons are quite common in the intake, even if someone has disconnected the PCV system.
If you really "Suppose" that hydrocarbons arent there. I really dont expect you to help much, and it's quite expected that to cover your stupidity you'll try and bash my troubleshooting and predict the voice of DOOM regarding head gasket.
Swallow your ego, learn to just keep your mouth shut when you dont know the answer and this wont happen so much.
Bye :)
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Discretesignals
Ultimate Carjunky
/ Moderator
Mar 10, 2015, 10:22 AM
Post #7 of 10
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Re: 99 GM 3.1 V6 whistle after intake manifold gasket replace
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I really don't want this thread to turn into a pissing match. I'm up for learning. Being a professional you are in a constant learning mode.
I'm curious on how HCs can get into the coolant system on that design. If the manifold is under vacuum, except during heavy acceleration and when the engine is off, and the coolant system is normally under pressure, how does the HCs make their way into the coolant system?
When they were testing for HC, did they use an emission's analyzer? Was was the amount of HC detected? Did the HC rise as the engine got hot? If you blocked the PCV valve intake, did the HC go down? Just curious on how you came to the conclusion of your theory.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Tom Greenleaf
Ultimate Carjunky
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Mar 10, 2015, 10:33 AM
Post #8 of 10
(1900 views)
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Re: 99 GM 3.1 V6 whistle after intake manifold gasket replace
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You used the wrong word when talking about cars. Google out what the definition is of a "Hydrocarbon" and you'll get tons of things. When talking cars and HCs I don't expect liquid fuel called other that just that.
We'll, this read was more fun than chopping ice outside. Have fun learning how you messed up your job even seemed to make it worse but KNOW SO MUCH!
Have a great day,
T
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GC
User
Mar 12, 2015, 8:13 AM
Post #10 of 10
(1870 views)
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Re: 99 GM 3.1 V6 whistle after intake manifold gasket replace
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DS hit it on the head. How would a coolant system under pressure suck up hydrocarbons from an intake under vacuum? That leak works the other way around. A head gasket leak will push combustion gasses (think VERY HIGH PRESSURE) into a lower pressure coolant system. Simple stuff. Wherever you heard that junk, dont listen. You said this engine was new to you, now you act like an expert?
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Willing to help, willing to learn... Rob
(This post was edited by GC on Mar 12, 2015, 8:14 AM)
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