no compression after rebuild... please help

[Boarderboy1316]

As the title says, I did a block rebuild with topline parts. I took the block to a shop so they could do the work. I got the block back and put it all back together with out having problems, it seemed. But now its all together and in, it doesnt start. I have 0,0,0,0 compression. Please help.

 

[Lunch_Box]

Head studs torqued down?

 

[project_tsi]

I dont see how any engine could have 0 compression accross the board. Sound more like you screwed up timing and bent all the valves, thus making it seem like you have 0 compression. Did you do a reverse leak down test? Do this and tell us what you find out. When I did mine, I too had 0 accross and w/ a leak down test I could here air rushing out my ex. ports, after I pulled my ex. mani off. I replace the valves, and now I have 160 accross the board!

 

[jltcat]

rings installed? timing? spark plugs? correct studs/ head gasket? correct clearances? check these; with 0 across the board should be a pretty easy diagnostic.

 

[Boarderboy1316]

i did a wet test and the piston rings are good.. this means it should be timing correct? bent valves, how possible if i havent started the motor since i put it back together?

 

[project_tsi]

i did a wet test and the piston rings are good.. this means it should be timing correct? bent valves, how possible if i havent started the motor since i put it back together?

You cranked the motor over correct? If not, then its not valves, but if you timed it, and cranked it over, trying to get it to start, then very easily, it could be valves. The engine doesn't need to start in order to bend valves. If the valves are in the way of the pistons, then the valves bend, just not as bad when the engine is not started, but either way, they are junked.

Do a compression reverse leakdown test, and listen to where air is coming from, if you can find it, then get back to us.

 

[1fast97gsx]

If you flip the intake cam gear upside down on accident ( 180 degrees rotation ) you will get 0 compression but no have any valve damage. Set your timing at tdc and make sure the gears are right side up when 1 and 4 are at the top.

 

[Boarderboy1316]

TIMING

My timing was off a quater turn, the crank was. Which, Im am quite sure isnt going to mess up my valves because none of the pistons are at TDC. I think I lucked out, did I?

 

[jltcat]

if it was me I'd pull the head just to be on the safe side. It would make me sleep easier at night.

 

[project_tsi]

TIMING

My timing was off a quater turn, the crank was. Which, Im am quite sure isnt going to mess up my valves because none of the pistons are at TDC. I think I lucked out, did I?

A quarter turn is alot, and it doesn't take mutch of being off for it to bend valves, I KNOW!

 

[OverboostXS]

Did you hand turn the motor first? If you just rushed and turned it over with the starter and your a quarter turn off at TDC you might be in some trouble. Hand turning will not bendvalves its an easy and safe way to realize that your timing is safe.

 

[Precision]

Sounds like you should have paid to have it profesionaly done. Might as well plan on taking'er back apart again, my money is on bent valves.

 

[Maglin]

Being as the stock cam gears are notched on both ends you have to be sure the cam gear dowls are pointed straight up when you set the valve timing. Sounds like you are 180* out and not just 90. That wouldn't hurt a thing. Plus if you didn't start it and just cranked it over off the starter you would have heard your valves hit your pistons and it would even stop the motor and usually not cause any damage as it's doesn't have enough force to bend the valves.

Just pull the timing cover off again and reset your timing. Then put some oil down the holes and check your compression. If you are using forged pistons your compression numbers won't be where you think they should be sometimes due to the fact that it might not seal good until it's warmed up.

I personally wouldn't go pulling the head off until I tried that. Head gaskets aren't cheap. Also do a leak down test once you know it's right to see if you possibly did bend any valves.

 

[Morphius]

Given your timing was off, I'd do what everyone else is suggesting, pull the head and get it checked to be sure the valves aren't bent.

My other suggestion is lifters. This exact situation has happened to me twice. Installed a rebuilt head and got zero compression. The fix was to bleed the lifters as they were pumped up enough to just hold the valves open. If the valves check out, I'd move to the lifters. In the VFAQ, there is an explantion on how to remedy this.

 

[Ybnorml]

Your intake cam could be 180 off even though the cam gear marks lined up. I had that problem and had very little compression. I turned it over and life was good as far as cranking.

 

[1fast97gsx]

Your intake cam could be 180 off even though the cam gear marks lined up. I had that problem and had very little compression. I turned it over and life was good as far as cranking.

He already established his timing was off.

I would just fix the timing and hand turn the motor. If all feels well then do a compression test. Usually a bent valve will show up then. If compression is normal then start her up and be thankful.

 

[endlessMyk]

Someone once said that cracked pistons could result in a 0 compression... The only reason I bring this up is because my timing jumped teeth and now I'm getting 0's across the board... Hoping it's just all my valves are effed up.

 

[Old Mitsu Tech]

Always hand turn an engine after installing a timing belt. You are gambling with hundreds and in some cases thousands of dollars. I worked at Mitsubishi in the early 90's when they had the timing belt problem. I've installed a whole crap load of them and I still hand turn every last one of them. I never install and crank engine. Reinstall the belt, hand crank to see if anything hits. If it does, you will feel it bump on your ratchet or whatever you are hand cranking with. If it passes that test, put it all together and fire that bad boy up. If it won't start and has a whiny nasaly no compression sound, do a compression test. If it fails, proceed with a head removal. If this is the case, you will be living testimony to the next guy who asks that question "to crank or not to crank"

Good Luck

 

[bullettdsm]

TIMING

My timing was off a quater turn, the crank was.

Fellas,
It looks like he is implying that he had his cams set properly but somehow his crank was 1/4 turn off TDC. By my estimation that can produce a pretty good OUCH! Sorry Boarderboy1316, my condolences.
MB