Any way to tell if manifold is warped or just gasket need replaced?

[Rivieraracing]

But these motors have a dry intake... so there wouldnt be any coolant loss with a bad intake

I haven't messed with mine at all and thought it was as well from others on here mentioning it but then went outside and look at my haynes manual and it said that one cause of coolant loss could be an intake gasket gone bad!! Stupid manual!! lol

 

[ATL]

the only way i know how to lose antifreeze without it actually leaking out, is head gaskets. usually if this happens, the pressure from the cooling system slowly leaks into the combustion chamber when u turn the motor off. if this is going on, the truck will idle rough for a min everytime it has sat long enough for the coolant to get in there. does your truck idle rough only when cold, or almost everytime you crank it? if this is happening, a simple fix until you get gaskets is getting a pressure release radiator cap. when you turn the motor off, you can release the pressure so its not leaked into the motor

 

[endlink]

Rough idle only occurs when its cold but its also causing misfires. A friend of mine brought by his "tech 2" and scanned to confirm the random misfire in all cylinders and agreed that it is most likely the intake manifold or gasket as he has changed many of them. As far as the coolant.... I'm going to keep better track of it to confirm or deny the possible head gasket leak. I cant tell if the cooling system has dripped any coolant because of the snow/water on the floor of my garage everyday due to the weather. Seeing that I'm on a budget I'm going to order new intake gaskets and hold off on the manifold itself until I pull it off. Anyone have a recommendation on where to buy the gaskets? Thanks for all the help.
- Ed

---------- Post added at 07:23 PM ---------- Previous post was at 05:47 PM ----------

update- not only did I have random misfire code but also lean bank 1 and lean bank 2. I'm going to check the fuel pressure tomorrow just to rule out the regulator or pump (pump was replaced 20k miles ago).

 

[endlink]

UPDATE: got a fuel pressure gauge and measured 50 psi at the rails while at idle and would decrease to 45 psi when rev'd to 3k rpm. I then disconnected the vac line to the fuel pressure regulator and the pressure shot up to 60 psi at idle. So this would mean the FPR is the problem correct?

 

[ATL]

no, 50 at the rail is great

 

[endlink]

no, 50 at the rail is great

I just read on another forum that 55 - 62 is gm's spec. and many people are having problems when it drops under 49 psi. So I guess I'm getting conflicting information.

 

[ATL]

i just replaced mine last week. it tested at 25 psi and it would drive fine but ocassionally would drop to 0, bang on tank, up to 45 psi then right back to 25. i installed a new acdelco pump assembly and im getting 53. from all info ive seen, 50-55 is ideal

 

[endlink]

i just replaced mine last week. it tested at 25 psi and it would drive fine but ocassionally would drop to 0, bang on tank, up to 45 psi then right back to 25. i installed a new acdelco pump assembly and im getting 53. from all info ive seen, 50-55 is ideal

I'm not thinking its the fuel pump but the fuel pressure regulator... which is mounted on the rail. I did look it up and GM spec is 55 - 62 with key on engine off.

 

[Skizzot]

Simple solution: If you're gonna replace the intake manifold you will need new gaskets anyways. Start by buying the gaskets and if that doesn't correct the problem buy the intake manifold on eBay and the nearly new gaskets will be acceptable for reuse.

One suggestion....before pulling the intake manifold thoroughly inspect the bolt channels that run under it. They are extremely difficult to inspect! I did mine a few weeks ago and it turns out that there was a small nut in there from an old repair which dropped into the intake. I didn't hear it when wiggling the IM out but certainly heard it when I fired the engine up. It blew apart cylinder 6 to include the spark plug threads. $2000 later I swapped the engine and can't figure out what the hell the issues are with the swapper. Good luck.

Also, it appears that you're debating the cause of your problems. Besides the carb cleaner trick to test for intake leaks there is also another nifty trick. Pull the air intake hose from the throttle body and plug the TB with a small rubber ball that kids would play with. Then pull the vacuum line to the brake booster and blow cigar smoke into the line. Keep blowing smoke until pressure builds and look for any smoke escaping from the intake manifold gasket area.

 

[endlink]

Simple solution: If you're gonna replace the intake manifold you will need new gaskets anyways. Start by buying the gaskets and if that doesn't correct the problem buy the intake manifold on eBay and the nearly new gaskets will be acceptable for reuse.

One suggestion....before pulling the intake manifold thoroughly inspect the bolt channels that run under it. They are extremely difficult to inspect! I did mine a few weeks ago and it turns out that there was a small nut in there from an old repair which dropped into the intake. I didn't hear it when wiggling the IM out but certainly heard it when I fired the engine up. It blew apart cylinder 6 to include the spark plug threads. $2000 later I swapped the engine and can't figure out what the hell the issues are with the swapper. Good luck.

Also, it appears that you're debating the cause of your problems. Besides the carb cleaner trick to test for intake leaks there is also another nifty trick. Pull the air intake hose from the throttle body and plug the TB with a small rubber ball that kids would play with. Then pull the vacuum line to the brake booster and blow cigar smoke into the line. Keep blowing smoke until pressure builds and look for any smoke escaping from the intake manifold gasket area.

Thanks for the pointers. I'll have to try the cigar smoke trick. The only issue with ordering the gaskets first is the fact that I would be stuck with finding an OEM intake manifold. If I go with an entire new dorman intake manifold it will come with gaskets for much less $.