Ok folks, a little more involved

[blacksnapon]

A double overhead cam vehicle, with a v8 is showing low compression on one bank of cylinders. Vehicle has no outward signs of trouble (leaks, misfires, overheating, etc.) Technician a says that one timing chain is off one tooth. Technician b says there is a vacuum leak on the intake manifold on that side. Who is right? Tech. a--Tech. b-- both--neither.

[slmann]

I'm just guessing but I say tech A.

[O'Rattlecan]

valve leakage...

Although I should be guessing timing chains on one cam, otherwise you wouldn't have mentioned the DOHC setup.

Ryan

[lenny1carl]

you show offs with more than 1 cam

[mrfixit]

Neither. One tooth isn't enough to cause all cylinders to read low, as it isn't opening the exhaust valve just yet as it has crested the power stroke. especially on a v8. couldn't be the intake, as that has no bearing on the compression. could be warped head, bad bearings/wrist pins/rings/valves, but not the intake unless the intake ports were severely restricted. Being as it is the whole bank, I'm going with warped head as my initial look-see.

[6L PWR]

I'll go with neither also. Vacuum leak? That shouldn't cause low compression. Maybe the chain off by one tooth, but I don't think so.

[Brian_B]

Subscribing. These threads are interesting if nothing else.

[O'Rattlecan]

valve could be bent..?

Ryan

[Blue Goose]

Neither.........I'm looking down for the answer, but all I can see is my feet...:rolleyes:

[Brian_B]

Neither.........I'm looking down for the answer, but all I can see is my feet...:rolleyes:


Did you lose weight recently? :redface:

[Blue Goose]

You dawg!!!! You were the last one I was expecting an answer like that from...I was expecting something like that from the usual list of suspects and now I have to add you to that list...

[mrfixit]

We've been training him....

[Brian_B]

Ryan was not here so I was filling in. :)

[Blue Goose]

It's showing in his posts....

[mrfixit]

Ryan's not here??? he guessed the bent valve....!

[Brian_B]

Ryan's not here??? he guessed the bent valve....!


Shhhhh! He was not supposed to notice that. :rofl:

[O'Rattlecan]

just tell brad to turn his resolution up to 1600x1200, and you won't hear from him for a few days.

Ryan

[mrfixit]

It's OK: Remember GOOSERULE #37: ALWAYS own up to your abuser status. It keeps him from dozing off at the computer.

[blacksnapon]

It's OK: Remember GOOSERULE #37: ALWAYS own up to your abuser status. It keeps him from dozing off at the computer.Ya mean he can count to 37?

[mrfixit]

Which HE? Oh, never mind... don't want to embarrass the both of them...

[Fellro]

I've seen head gaskets make an entire bank go low... but it would be possible for the one tooth to change the compression a bit I suppose... haven't dealt with dual overheads much. Rather have a chain if I can...but if the time is off late, it could bend all the valves on that bank too, if it is an interference motor.

[mrfixit]

It seems ford didn't learn anything buying Jaguar, or jaguar didn't tell them everything :rofl:

[blackhat620]

I vote "a" timing chain off one tooth. Vacuum leak won't do it, but off one tooth on the timing chain can cause one bank to have an open valve in all cylinders since on a dual cam setup one cam works the intake valves and one works the exhaust valves.

[mrfixit]

.... since on a dual cam setup one cam works the intake valves and one works the exhaust valves.
Ummmmm, on a DOHC V-8, I do believe that is physically impossible.
But read my retraction below, because I was wrong.

[6L PWR]

I do believe that is physically impossible.So is the fact that you're still alive, but yet, you keep posting. :rofl: :nana: :rofl:

[mrfixit]

Ummmmm, on a DOHC V-8, I do believe that is physically impossible.
Actually, thanks to the help of a very smart friend, I found out there are such engines about.... my apologies. But at least I looked into it, right?? Oy.. to be me sucks sometimes.

[mrfixit]

So is the fact that you're still alive, but yet, you keep posting. :rofl: :nana: :rofl:
Just cuz you can't keep up is no reason to taunt....

[Blue Goose]

Just cuz you can't keep up is no reason to taunt....
Hell, I gave up keep'n up with you.......so I just yield the floor to you...

[mrfixit]

Good thing; I'd mop it with you.... Nooooooo I wouldn't, yer too nice of a guy for that. But it DID sound funny, didn't it?