4.1 help

[shmed]

ok heres the deal new 4.1 was running good for the for the first couple hundred k now the vac gauge is low between 5 an 10 used to be 17 20. it swings at idle 5-10 , no exhaust leaks. or vac leaks
that I found, plugs looks similar, put theres a noticeable loss of power now. brought it in to the mech says 4 an 6 aren't working properly?
im thinking camshaft?
any advice or tips I should look at/
thanks

 

[Nick Micale]

ok heres the deal new 4.1 was running good for the for the first couple hundred k now the vac gauge is low between 5 an 10 ..........

that I found, plugs looks similar, put theres a noticeable loss of power now. brought it in to the mech says 4 an 6 aren't working properly?.........

What does "not working properly" mean? You do not have to be a tech to know that, did he do a compression check on all the cylinders?

First guess is your head gasket is blown, and could be leaking between no. 4 and 6 cylinder?

 

[bison]

Do a compression test. I'm sure you can hear if the head gasket is out between cylinders just by cranking it?


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[earlbrown]

And a leak down test would be even better.

When you say the vacuum gauge moves at idle... is it a swinging move or more of a tick in one direction?


Also, does this engine have a flat tappet cam?

 

[shmed]

thanks for the replys, Im not sure what the tech did its my sons car,
I did a compression test this am I have 135 in all cyclinders except 4 it read 0!!!
I don't have a leak down tester suppose I can google a diy one.
yes its a flat tappet cam.
so should I pull the head or is there another test I can do?

 

[hiboom]

bent valve on 4 ?

 

[shmed]

update removed the rockers from passenger side did another compression test on 4 an hit 150 ..
thinking about putting some air into the engive via number 4 not sure tho
advice?

 

[shmed]

well after looking an looking found a broken valve spring. hopefully this will be the cure

 

[earlbrown]

yep. with a broken spring, you had a dead hole.

While you're there I would pull both valve covers, get a dial indicator and measure all 12 cam lobes. Buick V6's like to eat flat tappet cams almost as much as they like to eat Mustangs.