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Stumped, Motor won't start new build

13980 Views 53 Replies 12 Participants Last post by  LaW, 
LaW
I figure I would start a general thread and get some thoughts.

History:

Bought a built block done by Sandbeck Race Development. The block was a used 702 casting but new internals (Crank, Bearings, Rods, Pistons, ARP studs). Heads were brand new dual avcs and had full P&P, GSC Valve springs, Supertech valves and GSC cams.

Had the machine shop that did all the head work do the assembly and timing. Shop was T&T Racing Engines and they do a large volume of Subaru rebuilds (Do machine work for P&L last time I checked).

When I got the motor from them they set the initial timing wrong on the drivers side (2 and 4) and I corrected immediately, shouldn't have caused any interference.

Installed motor and the car would not turn over. You could hear it starting to fire but just piss out. So I did a quick compression check.

1 & 3 were both 120psi
2 & 4 were both 55psi the same

I have spark on all 4 plugs, and fuel is getting to all 4 cylinders.

So my thought here was that the low compression was causing the car not to fire. I assumed it may have been head related and actually took the motor down to T&T for them to double check the head work and valve clearances as I found a few of them to be a bit tight.

I did my own leakage test prior to taking it down and came up with about 7-10% on all 4 cylinders. I didn't think it was too high considering rings were not seated. Machine shop verified the numbers and actually got better leakage #'s @ ~5% on each cylinder. I contribute this to my compressor not allowing me to get consistent readings on my tester using high PSI

Upon inspection they did find a couple valve clearances that were too tight and corrected them but they were on the 1 & 3 bank. No issues with 2 & 4 heads, head gaskets looked fine.

I am about to drop the motor back in to verify the compression test results but have really no direction if that fails again. I am only dropping the motor in to connect the starter for this. I am not going to waste time installing everything until the motor checks out.

Could this be AVCS solenoid related?

Another theory is that I am using a small Odyssey battery that was hooked up to a booster. Maybe it ran out of juice to crank the new motor over. I am going to be using a brand new battery interstate this time around.

I thought with the compression being equal between 2&4 it may be head gasket related. They are installed correctly from what I have seen. Being brand new factory gaskets on a car that has not started yet I can't imagine that is the issue.

Any thoughts would be helpful. I have myself, friends and the shops a bit confused with what is going on here.
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Fujiwara
Try swapping crank sensors if you can get your hands on one, Double check your fuses, and make sure the tune is set for startup

Next check fuel return -- makes sure fuel is getting past the injectors and running through the return -- just pop off the return line and cycle the key -- fuel should come out of the line.

Check for spark -- make sure the coil packs arc when you attempt to crank her -- the simple method is remove the coil pack, pull off the boot and then hold the sucker close to the block -- the professional method is a spark test kit if you want to try to borrow one from advance auto or something.

When in doubt, post up plenty of pictures of it all in, and maybe post up a link to a startup map that is unlocked.
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willub
Are you 100% that you fully corrected the timing issue? I was sure I set the timing properly on a legacy gt, but I set it on the wrong mark on the crank. Car wouldn't fire and was actually puffing out of the intake. I turned it over by hand to ensure there were no clearance issues before attempting to start it so no damage was done. Re-checked the timing, slapped myself in the face, corrected it and she fired right up :)

I don't know enough about avcs to comment on that, but if you're sure the timing is correct I would look in to the avcs system. No way it's the head gasket.
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LaW
willub said:
Are you 100% that you fully corrected the timing issue? I was sure I set the timing properly on a legacy gt, but I set it on the wrong mark on the crank. Car wouldn't fire and was actually puffing out of the intake. I turned it over by hand to ensure there were no clearance issues before attempting to start it so no damage was done. Re-checked the timing, slapped myself in the face, corrected it and she fired right up :)

I don't know enough about avcs to comment on that, but if you're sure the timing is correct I would look in to the avcs system. No way it's the head gasket.
Click to expand...


Yeah I have done a few Subaru timing belts in the past.

I had a new gates timing belt, the crank pulley is lined up with the hash mark with the hash mark on the oil pump, so not lined up with the arrow.

The single marks on the cam pulleys are lined up with the lines on the timing belt and belt covers and the double lines are lined up pointing each other.

When I first got it back the shop had lined the double lines on the drivers side with the belt cover/timing belt so I knew it was off almost right away.

Compared my timing to 2 other motors sitting at a friends house just as a sanity check and everything looked identical.
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LaW
Fujiwara said:
Try swapping crank sensors if you can get your hands on one, Double check your fuses, and make sure the tune is set for startup

Next check fuel return -- makes sure fuel is getting past the injectors and running through the return -- just pop off the return line and cycle the key -- fuel should come out of the line.

Check for spark -- make sure the coil packs arc when you attempt to crank her -- the simple method is remove the coil pack, pull off the boot and then hold the sucker close to the block -- the professional method is a spark test kit if you want to try to borrow one from advance auto or something.

When in doubt, post up plenty of pictures of it all in, and maybe post up a link to a startup map that is unlocked.
Click to expand...
Will try crank sensor.. Fuses are good and my tuner actually stopped by to make sure the injectors were set correctly and we even tried tweaking a few settings with little to no difference. My tuner actually is running almost identical modifications and his new built motor fired up no problem.

Fuel system is new with this build using the FL FPR so will take a look at that as well.

I did check spark and was good on all 4.

I am open source so posting the map may be an option once I get a battery in to download the current rev.

Thanks
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willub
I would guess it's avcs related then. One of your cams must be stuck fully advanced or something so the valves are slightly open on the compression stroke. That's my guess at least.
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LaW
willub said:
I would guess it's avcs related then. One of your cams must be stuck fully advanced or something so the valves are slightly open on the compression stroke. That's my guess at least.
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The solenoids were taken out and cleaned after the bearing failure and were probably the only parts not replaced with new. Theoretically if it were an AVCS solenoid that was stuck I should be able to move it to the other side and see the compression issues follow.

I don't know much about AVCS, I do understand how it works. Has anyone seen a motor not start due to a stuck AVCS solenoid? How much can the AVCS system advance/retard timing?

I did disassemble and clean out the cam gears on both sides also.
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Fujiwara
LaW said:
The solenoids were taken out and cleaned after the bearing failure and were probably the only parts not replaced with new. Theoretically if it were an AVCS solenoid that was stuck I should be able to move it to the other side and see the compression issues follow.

I don't know much about AVCS, I do understand how it works. Has anyone seen a motor not start due to a stuck AVCS solenoid? How much can the AVCS system advance/retard timing?

I did disassemble and clean out the cam gears on both sides also.
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No -- even when IAG had the cams that were improperly drilled, I believe the car still started. 30 degrees is the max IIRC

Best way to tell if AVCS is off is to log it.

If you're worried about them, try unplugging them -- the engine should still start.
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LaW
Thanks. You can tell I am stretching for a cause. I just haven't seen good leakage and low compression. Especially low compression on one bank being equal like that.
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Fujiwara
I understand bud, that's why I went through a list of steps for the major issues that could cause this -- post up what you try and what happens
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LaW
So just wanted to update the thread.

Dropped the motor in last night and did a compression test.

Before taking it back to the machine shop compression was 1 - 120 3 - 113 2 - 50-55 4 - 50-55

They did have to change the valve clearance on the valves for #3 and new numbers are:

1 - 120 3 - 120 2 - 50 4 - 50

So still 2 and 4 are very low. Keep in mind this motor has never started so I am not sure if cylinders were washed out on 2 and 4 to cause this after my first go around (tried to start it many times with no luck). I am going to try putting some oil in the cylinders and testing again to see what the result is.
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STi Addict
:(

could it be a bigger bore due to more wear on the 2&4 side? (bigger than 1&3)
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LaW
So had a short break, tried putting some oil in the cylinder and that only changed compression about about 5 psi, 50psi -> 55 psi which is what I was getting a month ago.

Wouldn't the bigger bore cause increased leakage?
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Fujiwara
Wait... You have two different sized piston setups on either side? Or are you saying the Piston to wall clearance on one side is loose?

Both of those issues would make me want to slap the builder with a breaker bar. Small variances in piston to wall clearance between sides I would accept (final 1/2 thou hone is by hand), but mismatched piston sizing -- which changes the balance of the rotating assembly as a whole -- or boogered up piston to wall clearances -- leaving one side looser than the other, once again unbalancing a motor -- are things I would not accept.
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LaW
Re: Re: Stumped, Motor won't start new build

Fujiwara said:
Wait... You have two different sized piston setups on either side? Or are you saying the Piston to wall clearance on one side is loose?

Both of those issues would make me want to slap the builder with a breaker bar. Small variances in piston to wall clearance between sides I would accept (final 1/2 thou hone is by hand), but mismatched piston sizing -- which changes the balance of the rotating assembly as a whole -- or boogered up piston to wall clearances -- leaving one side looser than the other, once again unbalancing a motor -- are things I would not accept.
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No I was replying to the post above. All the pistons are the same size.
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IAG Performance
Fujiwara said:
No -- even when IAG had the cams that were improperly drilled, I believe the car still started. 30 degrees is the max IIRC

Best way to tell if AVCS is off is to log it.

If you're worried about them, try unplugging them -- the engine should still start.
Click to expand...

Max AVCS is actually 45 retard on the exhaust side. But as Fujiwara said, it won't keep the car from starting or running for that matter. Additionally, AVCS work on oil pressure. If the car isn't started, you don't even have enough pressure for it to move. It is not an AVCS issue. I am inclined to say that at one point or another, the Cam timing was set incorrectly and either the motor was rotated hard enough by hand or cranked enough to bend valves. The other possibility is you do in fact still have the cam timing incorrect at this point. Either way some pics of your timing marks would help us help you.

Regards,

JJ
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Sabrewings
I know it's a lot of work, but you could swap sides with the cams. See if the problem follows. You might have an incorrect cam. If leak down is the same, but compression is seriously down, you have a valve timing issue. AVCS does require oil pressure to move, so I wouldn't worry about that.

The bump in PSI after squirting oil makes sense because your rings are fresh. I don't feel like the pistons or rings can be the cause at this point. Unless you have shorter rods on that side... :notsure:
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LaW
IAG Performance said:
Max AVCS is actually 45 retard on the exhaust side. But as Fujiwara said, it won't keep the car from starting or running for that matter. Additionally, AVCS work on oil pressure. If the car isn't started, you don't even have enough pressure for it to move. It is not an AVCS issue. I am inclined to say that at one point or another, the Cam timing was set incorrectly and either the motor was rotated hard enough by hand or cranked enough to bend valves. The other possibility is you do in fact still have the cam timing incorrect at this point. Either way some pics of your timing marks would help us help you.

Regards,

JJ
Click to expand...
JJ,

Thanks for the reply.

I will try to get a picture of the timing marks, I have set a few motors before and compared timing to my friends 2 spare motors and they all look fine to me.

The machine shop that did the heads bolted them to the block for me. When I got it back first thing I did was try to hand turn the motor to make sure everything was a good and I only turned it about 1/4 of a turn when I could feel some interference. At that point I saw the timing marks were way off from where they should have been on the bank that I am seeing the low compression on.

I stopped right there and removed the timing belt and reset the timing. Informed the machine shop. I am pretty sure there were no bent valves resulting from this. The shop also removed the heads a week ago and went through and didn't see any issues, and the motor was showing 5% leakage on all 4 cylinders.

I can confirm that with the crank at the correct position (hash lined up with hash on oil pump) that the single timing marks on the cam gears line up with the marks on the belt covers and both double hash marks on the cam gears line up in the center. I can still take a picture of it if you would like.

They returned the motor with the belt on again and the belt marks were also lined up with the timing marks correctly.
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IAG Performance
Sabrewings said:
I know it's a lot of work, but you could swap sides with the cams. See if the problem follows. You might have an incorrect cam. If leak down is the same, but compression is seriously down, you have a valve timing issue. AVCS does require oil pressure to move, so I wouldn't worry about that.

The bump in PSI after squirting oil makes sense because your rings are fresh. I don't feel like the pistons or rings can be the cause at this point. Unless you have shorter rods on that side... :notsure:
Click to expand...
Cams can not be swapped side to side btw! ;)
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LaW
IAG Performance said:
Cams can not be swapped side to side btw! ;)
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I was just going to reply to that myself. Not possible as they are quite different.
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