Compression test results!!!

[james_9876]

Really?? Oh sh.....

That may be my prob then. Question though, it the Timing belt IS, JUST SO HAPPENS TO BE over torqued, then if I loosen it, run the motor through a couple of heat cycles and let it cool down overnight with the block pull itself back straight? Or am I looking at boring it over?

Just wondering if I'm fixing my Geo this weekend and driving it for a while or doing the fix on my Supra.

Much Appreciated in advance.

Later

 

[Poodles]

it SHOULD go back straight, but make sure you loosen it, then retighten to the proper spec...

after breaking fasteners, ect... I ALWAYS go by the torque specs in the TSRM when I touch my car...

 

[wardog]

Ok im set for sunday, i gotta work tomorrow!!!! So sunday ill retorque head and pullley first. Im loosin oil like crazy 1 quart a week, thats why i wanna replace the valve stems. If my compresion doesnt get fixed after retorque im gonna freshen up the engine new rings and bearing hope i dont have to get to that point. Any pics of what the damn VALVE SPRING COMPRESSOR LOOK LIKE...

 

[aberabee]

good luck with the sunday work...hope you have a backup car while the supra is down!

 

[james_9876]

True dat. So you need a valve spring compressor with the head on the car?? or off?

There are different ones for how you wanna do it.

Later

 

[cuel]

Gonna need a whole lot more than a spring compressor to do the valve stem seals with the head on the motor. The valves won't hold themselves up in the head.

Good Luck....

 

[tte]

You will need to blow compressed air thru the spark plug holes to hold the valves up when you remove the springs to do the seals.
I have heard of people also pushing clear silicone hose through the spark plug hole till it coils up and fills the gap in the cylinder. The piston for that cylinder will have to be at top dead center so you wont need the sapce in the cylinder will be minimal.

Cheers,
Roy

 

[james_9876]

Yeah, I'ld say put it at TDC on whichever cylinder you're working on and pressurize it. you can usually retrofit a compression tester ( just take the shrader valve out) and use a regulator.

Good luck.

 

[wardog]

Well guys i did all the work that day and still the same . I added some oil to the cylinders and it raised the compression. I just dropped off the engine with my mechanic so that he can take it out. Tomorrow im gonna pick it up put it on the engine stand and tear it down. My plans are to put new bearings, rings, and all new seals including the valvestems on the car...But ill keep u guys posted tomorrow night after i tear it down....hopefully with pics :aigo:

Guys what size are the bolts i need to put the engine on the stand ....?????

 

[greg88]

Guys what size are the bolts i need to put the engine on the stand ....?????

10x1.25x100 worked fine for me.

 

[wardog]

Thanks for the quick response ill be on my way this afternoon to go get them ...

 

[IJ.]

you overtorqued the timing belt idler pulley more than likely...

overtorque the bolt, and it will deform the first cylinder enough to drop compression.

tighten to 36lbs

Once done it's fucked it won't spring back....

 

[greg88]

Once done it's fucked it won't spring back....

I just can't wrap my mind around that. How can a single
over-torqued bolt can deform a cast iron block enough to warp a cylinder?

 

[IJ.]

The Tensioner bolt is large diameter and the cylinder wall it bolts to is quite thin.

Even at 36 ft/lbs I've measured a half a thou deformation, way back I trashed one of my blocks by over tightening it, there's a quarter sized spot in the bore that the rings have never touched and the motor had quite a lot of blowby on the dyno.

 

[Frank Rizzo]

I thought the bolt contacted the cylinder wall, I didn't know it actually threads into it and pulls it away from the piston.

I wouldn't blame the torque spec for the problem though, I'd blame an incorrectly calibrated torque wrench, or a gorilla. I torqued mine to 36 ft/lbs with a snap-on torque wrench and my no.1 cylinder has 185psi compression and 2-5 have 180-185.

Maybe, just maybe, it happens when you torque the tensioner bolt with the no.1 cylinder NOT at TDC. Or when you are removing/installing the timing belt and when you release the tension and tighten the tensioner with the tension on the belt relieved......

<ducks for cover> :kloguck:

 

[wardog]

Well guys as of 8 o'clock central time the engine is out the car and all the attachments are off. There is no sign of bhg my cosmetic mhg has no been damaged at all. The head looks good all the valve seat nice and tight to the head, and all i found i the water passages is somehting white like if it was salt with some elmers glue.

1st question i was lossing water from the radiator and whe i started the car i heard the waterfall sound by the heatercore WHAT CAN CAUSE THAT MY MHG LOOKS PERFRECT???

2ND is there a way to find out on my own how if ineed to do a .20 over on the block?? Any advice or experiences are welcome thank u..ill try to post some pics soon of the cylinders and mhg....

3rd were do i get a clutck disk that can fit my spec stage 3???Ohh im gonna have a shop resurface the cluch and flywheel once im at it ...

 

[IJ.]

Frank: The half thou deflection happens each and every time you torque the bolt to 36ft/lbs there's no if's or buts about it.

Over tighten it and the deflection is more to the point it won't return when undone.

I have my blocks bored and honed with a Tq Plate and the tensioner bolted in place so when the motor is assembled the hole is round and true.

It's a small thing and probably won't make any difference at all unless the bolt is pulled down too hard.

I have my original block here that I now use as a dummy during fabrication as it was on it's last O/S and can't be bored again.

WD: Measure it?

Stock is 83mm on the button.

+20 thou is 83.5mm

+40 is 84mm

 

[Sawbladz]

I just can't wrap my mind around that. How can a single
over-torqued bolt can deform a cast iron block enough to warp a cylinder?

This is elastic and plastic deformation. Elastic refers to when the material reverts bask to its original position once the applied force is removed. There is a point at which an applied stress will cross over into the region of plastic deformation. This point is the proportional limit. Plastic deformation is when the stress is no longer proportional to strain. This is a permanent, nonrecoverable deformation.

Sorry, been reading my textbook lately and thought I would share. lol

 

[wardog]

Ok time to update whats goin on, so i decided to do a stock rebuild on the block and head. I took the head to get rebuilt and its back all clean and silverish. I took the block apart and it looks like an uneven wear patern on the bearings there is no copper showin though on any of em . I talk to the shop that rebuilt my head and they charge me 375 to do all the machining and assembling and deckin the block all i need is to bring the parts to them. Im gonna head out to take them the block so they can mic it and tell me what size bearings that i need and im gonnna do a .20 over on the block all stock rebuild. Im gonna give the ebay full engine rebuild kit a try its all nippon pistons , acl bearings , water pump, oil pump, timing belt , gaasket kit etc for $300 plush shippin.and ill let u know how its doin as time passes by ....well im out to deliver the block ill post later tonight

 

[wardog]

here are some pics of the build :aigo: