Can hear air on manual turn over

[jukematt]

I'm rebuilding my engine due to spun rod bearings. I'm just wondering, I have the head and pretty much everything on the block (turbo, intake manifold, etc) except the oil pan. When I am turning over the engine manually, I can hear the air escaping out the bottom of the block. We tried doing a compression test and the gauge after two turns went to about 30 psi, then two to three more turns went to about 60 psi. But each time a piston comes around I can hear the air escaping form that cylinder.

Is this normal? Or could I possibly have a problem?

 

[Sebba]

Some air will escape, and that's normal. it shouldn't be easy to turn over, you should have to apply a LOT of force to push it through a compression cycle. Also compression testing it by turning it over by hand are invalid. Bolt up the starter and do it on the stand. That'll tell you.

Sounds like either the cylinders are out of round, the rings weren't gapped correctly, or some other clearance error.

Either way, take it apart and figure it out.

 

[jukematt]

It is pretty tough to turn but not REALLY tough. I checked the gap on the rings and they were within spec according to Haynes. Also, I realize the compression test wouldn't work very well but I thought maybe I could get a general idea of how close each are to each other but I'll wait to do it when it is in the car.

EDIT: I also had the local engine machine shop check the block, clean it, and align hone for the new rings so everything should be good.

 

[Sebba]

No telling how competent they are at their jobs.

I would crank it over on out of the car and confirm.

 

[3kgt2nv]

It is pretty tough to turn but not REALLY tough. I checked the gap on the rings and they were within spec according to Haynes. Also, I realize the compression test wouldn't work very well but I thought maybe I could get a general idea of how close each are to each other but I'll wait to do it when it is in the car.

please tell me you are not reusing the old rings.

and why did they align hone the block? did you get a new crank?

i am going to guess you are trying to say they honed the cylinders. which if they did and your using the old rings thats your issue.

 

[Sebba]

please tell me you are not reusing the old rings.

and why did they align hone the block? did you get a new crank?

i am going to guess you are trying to say they honed the cylinders. which if they did and your using the old rings thats your issue.

Nobody could be that stupid.

If you've got the common sense to take a block to a machine shop, it makes no sense that you would then reuse something as elementary as piston rings.

 

[jukematt]

Oh no way I would do that. So my crank was damaged to .015" but I wanted the ACL race bearings so I got a new crank which had been machined and polished to 0.010" and got oversize bearings and new main bearings. I bought new piston rings. They did not hone the cylinder walls. They only align honed for the new rings I bought. In order to do that, I gave them my block, my main bolts, and the main bracket or whatever it is called that the main bolts bolt onto.

 

[bryanwheat]

This is pretty normal with a fresh engine that hasn't been started yet.

 

[3kgt2nv]

I would at least surface hone the cylinder walls. but yeah then its pretty normal since the block isnt warm the pistons rings haven't expanded and sealed yet.

also make sure you correctly installed the rings and they are not key holed. the ring ends should be 90-120 degrees away from each other to help prevent key holing

 

[bryanwheat]

I would at least surface hone the cylinder walls. but yeah then its pretty normal since the block isnt warm the pistons rings haven't expanded and sealed yet.

also make sure you correctly installed the rings and they are not key holed. the ring ends should be 90-120 degrees away from each other to help prevent key holing

He said align hone for the rings, i assume that actually means hone the cylinders instead of align honing the main bores.

 

[3kgt2nv]

They did not hone the cylinder walls. They only align honed for the new rings I bought. In order to do that, I gave them my block, my main bolts, and the main bracket or whatever it is called that the main bolts bolt onto.

reread, I think he was referring to the main bearings and put rings by mistake

 

[bryanwheat]

reread, I think he was referring to the main bearings and put rings by mistake

If that's the case i hope he is prepared for the rings to never be seated in, .

 

[jukematt]

I meant to say rings not bearings. The guy that worked at the machine shop asked if I wanted to "do the cylinder walls" but I think me meant boring, Idk. I'm not too familiar with what is done at a machine shop, just what needs to be done. Honestly I don't know what all the terms mean but I told the shop what I was told to by some fellow DSMers and they understood. Sorry if that was confusing.

From the way it sounds from the replies, then what I have experienced is normal and everything is fine. Thank you all!

 

[bryanwheat]

I meant to say rings not bearings. The guy that worked at the machine shop asked if I wanted to "do the cylinder walls" but I think me meant boring, Idk. I'm not too familiar with what is done at a machine shop, just what needs to be done. Honestly I don't know what all the terms mean but I told the shop what I was told to by some fellow DSMers and they understood. Sorry if that was confusing.

From the way it sounds from the replies, then what I have experienced is normal and everything is fine. Thank you all!

So the cylinders were honed or they weren't? It sounds like you didn't do your research on things before jumping into a job like this.

 

[2slow4now]

If I read right it sounds like the op didn't have the cylinders honed. I would at least have them honed to put a cross hatch in the bores. If you don't the rings may never seat in.

 

[pauleyman]

They did not hone the cylinder walls. They only align honed for the new rings I bought

You are mixing up words on two different processes. You need to find out what they did or did not do. If a machine shop is honing a cylinder they should have had your pistons also. Align honing is what you do to the block where the crank sits. CYLINDER honing is where the pistons go. They call is align honing because you align all the bearing surfaces. Typically this isn't done. Not only must the bearing surfaces be round but they must be concentric as it has to line up with the drivetrain, seals etc.

 

[jukematt]

You are mixing up words on two different processes. You need to find out what they did or did not do. If a machine shop is honing a cylinder they should have had your pistons also. Align honing is what you do to the block where the crank sits. CYLINDER honing is where the pistons go. They call is align honing because you align all the bearing surfaces. Typically this isn't done. Not only must the bearing surfaces be round but they must be concentric as it has to line up with the drivetrain, seals etc.

Sorry if I didn't word things correctly, I'm just saying what I was told to do and what the machine shop asked for to do it.

And OK that makes sense. My engine has ~145,000 miles and when I pulled out the pistons I could still see crosshatching. I bought new piston rings but was reusing stock pistons and rods.

The machine shop only asked for my block, main bearing cap, and main bolts.

 

[bryanwheat]

Sorry if I didn't word things correctly, I'm just saying what I was told to do and what the machine shop asked for to do it.

And OK that makes sense. My engine has ~145,000 miles and when I pulled out the pistons I could still see crosshatching. I bought new piston rings but was reusing stock pistons and rods.

The machine shop only asked for my block, main bearing cap, and main bolts.

So they didn't hone the cylinders? Regardless to whether or not you can see crosshatch from a previous built it needs to be honed again.

 

[jukematt]

So they didn't hone the cylinders? Regardless to whether or not you can see crosshatch from a previous built it needs to be honed again.

OK well since everything is pretty much back together and just about ready to be put in, I will know if there is a problem by a compression test once I get it running right?

 

[arrowhead]

OK well since everything is pretty much back together and just about ready to be put in, I will know if there is a problem by a compression test once I get it running right?

NO, NO, NO.

Make sure of what you had done, by all you have missplain, the cylinder walls were honed, to at least brake the glaze on them.

You do not have to take the pistons to them only for a honing job.
Did you wash your block after you received it?
Did you oil the walls after you washed it?

Is the same friend that is advising you about the honing the same one that is going to help you put all back together.?

Will you be able to check bearing clearances. do not assume becouse the crank is shiny and pretty that it is correct?

arrowhead

 

[pauleyman]

You do not have to take the pistons to them only for a honing job.

You are correct but I do anyway. It can be sure of what is what if I can compare bore to piston size. A good machine shop will tell you what the piston to wall clearance is, bearing clearance etc.

 

[jukematt]

NO, NO, NO.

Make sure of what you had done, by all you have missplain, the cylinder walls were honed, to at least brake the glaze on them.

You do not have to take the pistons to them only for a honing job.
Did you wash your block after you received it?
Did you oil the walls after you washed it?

Is the same friend that is advising you about the honing the same one that is going to help you put all back together.?

Will you be able to check bearing clearances. do not assume becouse the crank is shiny and pretty that it is correct?

arrowhead

I have done a BOATLOAD of research on this build. I have never taken apart any engine before and have spent more time on the internet and reading the Chilton and Haynes than I have taking it apart and putting it together.

To answer your questions:

I did wash my block and head after receiving them. I did not know to until I checked online to see if I needed to. Then I also found some rather large metal shavings lying loose in the head and such so I'm glad I did.

I did oil the cylinder walls, thanks to Haynes.

Unfortunately, I am on the other side of the state working so my friend is not able to help me, hence why I should have been done several months ago if they had I'm sure.

I checked clearances with Plastigage.

I even torqued everything down that I found torque values to. Not just the crank bolt and such, but I'm talking about even up to the spark plugs. I do appreciate the advice so sorry if I sound like I don't.

 

[arrowhead]

Glad you did, and good on your reading and research.

I bet it will be a killer.