zero compression on all 6 cylinders

[survyor2]

One thing I'm confused about is how ALL cylinders have zero compression. If there was some interference I would think some of then would have bend. I mean, it is not possible for all the valves to be open when I turned the crank. And when I turned the cam gear, its not possible for all the pistons to be at the top. But let me think about this for a bit.

Thanks Dennis

 

[IJ.]

Yep same thought here, can't really think of a cause for 0 in all 6, even with a hole torched in the crown of a piston mine still made some cylinder pressure...

stupid question time is the intake open??

ie you haven't made a new gasket and forgot the holes??
(only thing I can think of that will make 0 in 6)

 

[survyor2]

Yep same thought here, can't really think of a cause for 0 in all 6, even with a hole torched in the crown of a piston mine still made some cylinder pressure...

stupid question time is the intake open??

ie you haven't made a new gasket and forgot the holes??
(only thing I can think of that will make 0 in 6)

hehe. yup. the intake gasket is stock. And I press the acceleration when I do the compression test.

 

[IJ.]

Pump up a cylinder and let me know what you find.

 

[survyor2]

I think i figured it out! I really hope it just this stupid...

I just rechecked the cam gears. I set the crank pulley to zero, again. And the cam gears were pointing directly left! wtf, I know I checked this, so I kept turning the crank until the cam gears were pointing up and there is a nick similar to but not the right one on the crank pulley. It seems every time I checked it, I looked down and saw the nick and thought i was right on with the timing.

Ok hopefully crazy moment is over.

 

[IJ.]

So a possible 24 bent valves seeing as you've been spinning it over for the comp test

Do the test I asked for please...

 

[BOOSTEDSUPRA]

I think i figured it out! I really hope it just this stupid...

I just rechecked the cam gears. I set the crank pulley to zero, again. And the cam gears were pointing directly left! wtf, I know I checked this, so I kept turning the crank until the cam gears were pointing up and there is a nick similar to but not the right one on the crank pulley. It seems every time I checked it, I looked down and saw the nick and thought i was right on with the timing.

Ok hopefully crazy moment is over.

haha been there done this......

So a possible 24 bent valves seeing as you've been spinning it over for the comp test

Do the test I asked for please...

unfortunatly this was my fate as i did the same lame ass thing. saw a mark on pully and cranked several times each cyl to do a comp test... my fingers are crossed.

 

[survyor2]

So a possible 24 bent valves seeing as you've been spinning it over for the comp test

Do the test I asked for please...

I will do this test like you asked but I need time to remove the intake manifold. I think you may be correct though. Everything is set correctly now and i do have compression but it doesn't look good.

1-115 2-105 3-137 4-102 5-130 6-121

w/ oil

1-125 2-115

:/

 

[Letsride]

Time to start pulling the head back off........

 

[survyor2]

I connected my tiny 2 galloon air compressor to the spark plug #2. The cam lob shows the valve is in the closed position. I dumped 20 psi of air into the cylinder and it was gone within 5-10 seconds. I listened at the throttle body and it was loud echo of hissing air.

 

[IJ.]

I will do this test like you asked but I need time to remove the intake manifold. I think you may be correct though. Everything is set correctly now and i do have compression but it doesn't look good.

1-115 2-105 3-137 4-102 5-130 6-121

w/ oil

1-125 2-115

:/

This is a bit frustrating Dennis, this goes for EVERYONE posting a tech issue can you please provide accurate details, I was going on the idea it had no compression across the board, now it has "some".

You don't need to pull the intake just open the TB and listen it'll be apparant if it's leaking or not, you're only doing a cylinder at a time so it's all going to end up in the plenum where you'll hear it.

Having said that it may have bent a bunch of Exhaust valves as well

 

[dbsupra90]

i think you are misreading that?

i thought he went from not being installed correctly and having 0 to installed correctly and now have compression but low? that's how i read it anyway.

glad you figured out the issue, sucks that you seemed to have wrecked some stuff in the process tho

good luck on getting it sorted.

 

[IJ.]

Right you are Dave
(Been looking at wires all morning not at my sharpest)

My "guess" as to the cause of all this is Dennis didn't take up the slack on the belt on the correct side then when the engine was cranked it's skipped a bunch of teeth, normally a non issue but with a big pair of cams it's bad..

 

[Another MkIII]

Right you are Dave
(Been looking at wires all morning not at my sharpest)

My "guess" as to the cause of all this is Dennis didn't take up the slack on the belt on the correct side then when the engine was cranked it's skipped a bunch of teeth, normally a non issue but with a big pair of cams it's bad..

My guess too, but from the sound of it, its too late now, what's done is done.
-AM3

 

[survyor2]

So you guys are thinking that just having the cam gears set wrong (based on the nick in my crank pulley) in itself its not the real issue but actually that the belt slipped? I don't think the belt slipped at any point. It was at the nick were i put it, then it was at the true 0 were I put it now.

I care more about avoiding this issue next time more that what happened this time. See if I got this right: set crank to zero, install head, install cams as close to straight up as possible so I don't have to turn them, install belt. Good?

Before I just installed everything randomly knowing I can just set it all to zero later.

Thanks guys

 

[Heavy D]

when you did the compression test, was the motor cold? i forgot where i seen this but could have been on SF, but a guy with a MK3 did a compression test when it was cold and got low numbers, so he warmed it up, and then got higher numbers, but i wouldnt want you to take the risk of doing more damage if you think something is wrong just for a compression test, just triple check every thing and if i can start up safe, give it a shot, even if its for couple second and if it feels safe do a full warm up and do another test

 

[afracer]

Got to be careful with timing belts...and chains too for that matter. One tooth off and it's not good. I was one tooth off on my SR20DET. Ran funky, power was all whacked out and it backfired like crazy until I took it off again and figured it out. At the very least find out how many cogs between each mark and count three or four times to make sure you get the right number each time...especially with an interference engine!!! Hope the damage isn't too bad. Initially I was thinking you might have had something stuck in between the head and block like a hose or piece of metal, that the head wasn't fully seated, but usually you'd find that out when you filled with antifreeze and it just starts pissing out as you initially fill it.

I'm going to be putting my 1.5JZ back together soon. Anyone know how many cogs there are between each timing mark? I used to have the number for a 1JZ, but not the 2JZ!

 

[black89t]

shitty.

i know this is a little of topic, but survyor2 you were saying you reused your mgh a couple time. did you resurface the head or block agian for the reinstall. just curious.

 

[survyor2]

shitty.

i know this is a little of topic, but survyor2 you were saying you reused your mgh a couple time. did you resurface the head or block agian for the reinstall. just curious.

no. with less than 2000 miles since the block and head were resurfaced. no overheating and the old gasket sealed well. As much as i pull the head I'd keep resurfacing it out of spec.

Dennis

 

[black89t]

thats good to know.


so what are you gonna do from here?