Motor back in, crank like it has no compression.
 

Just replaced the head gaskets in the engine, re-installed, and now it just whirls away without any compression noises. If I crank it by hand I can feel some compression. There is tons of fuel getting in, there is spark, we pulled the right valve cover to check the cam timing (the single dot on one between the two dots on the other), the cams are in the right place, the valves on the right are opening and closing nicely...

Thoughts? I'd rather not have to pull the motor back out.

Re: Motor back in, crank like it has no compression.
 

Recommend using a compression gauge to check the more easily accessible pistons. If there is no or low compression it would seem to indicate that the head gasket is improperly installed (assuming normal compression prior to head removal).

Lee

Re: Motor back in, crank like it has no compression.
 

Simple and most often incorrect things first...

How did you align the cam belts?

Re: Motor back in, crank like it has no compression.
 

Gaskets were installed and torques as per the FSM. The heads were machined and rebuilt by our machine shop. Obviously though something went awry in the installation. I don't have a comp gauge at the shop right now but will have it tomorrow.

The arrow on the crank sprocket points straight up and the cam sprockets are aligned with the marks on the timing covers. The lines on the belt match the marks on the crank and cam sprockets. I've had the timing belt in and out of this car a few times, never an issue.

Re: Motor back in, crank like it has no compression.
 

Just tried fooling around with the timing belt position, no difference.

Re: Motor back in, crank like it has no compression.
 

are the cams on the right side? The intake cams can be reversed without you realizing... Its prob not a good idea to ask why I know this. Also, the cams can be flipped upside down. They have alignment marks 180* on the gears. Best way to check this...

Pull the valve cover on the pass side (easy one) Check the intake cam has a RIN on it. If it does... pop the pulley on the exhaust cam and pull the cap seal off the intake cam and make the keyway for the exhaust pulley point straight up... The intake's keyway should be in the same position

If all is well... check on the other side too for proper keyway positioning... If all is well.... Light it all on fire cuz the motor is comming out

Tom

Re: Motor back in, crank like it has no compression.
 

piston rings? not seated or damaged? what oil are you using I heard it can affect how well the rings will seat. Where do you hear the air escaping?

Re: Motor back in, crank like it has no compression.
 

I actually did most of that. Pulled the pass valve cover off and checked. The cams say R IN and R EX in the proper spots. We also verified that the alignment dots on the backside of the cam gears match up.

So pull the pulleys, pop the intake cam caps, make sure all the keyways face up together.

The bottom end should be fine, it was running well when I took it apart. There is no evidence of scoring or damage on the cylinder walls. #5 and 6 have a tiny bit of blow-by, but otherwise all is well inside. I think if the piston compression was bad enough that the engine spun this freely I'd be able to hear them bouncing off the walls.

Re: Motor back in, crank like it has no compression.
 

What YT is saying is to make sure the Passenger side cam keyway grooves are pointing the same way, both up , and the Drivers side cam grooves are pointing the same way, but both down.
Naturally this is with the crankshaft set to its 0° position.

Re: Motor back in, crank like it has no compression.
 

Gotcha. That'll be first on the list tomorrow.

Re: Motor back in, crank like it has no compression.
 

If all else fails.:)
Wind the engine over till a piston is at the top of the stroke. If it is the compression stroke, it will have both valves closed.
If the piston is at the top of the exhaust stroke(valve overlap) both valves will be slightly open. Not too hard to tell.

Harvey.

Re: Motor back in, crank like it has no compression.
 

Thanks Harvey, I'll check on that. I'm going to bring the laptop and camera to work so I can snap shots and post them up. Hmmm... Laptop + backpack + motorcycle...

Re: Motor back in, crank like it has no compression.
 

This reference document may help some if you do not have it. I also have the shop manual sections pertaining to this in a PDF if you want it, I can Email it. Too big to post that one on here.

Lee

Re: Motor back in, crank like it has no compression.
 

Thanks Lee, I have Mitchell On Demand at the shop, but that's more detailed. I'll check things out and report back tomorrow.

Re: Motor back in, crank like it has no compression.
 

Alright guys, conundrum. Took the pulleys and caps off. On both sides the cam keyways are 180* off from each other (one up, one down). The little dots on the back of the right cams line up though. Are there two sets of dots?