Short Block Health Check?

[atkinson40]

Waiting on rings. 

 

Looked down at the top of the pistons in the old block and see a big ol' honkin' gap

between the piston wall top and the cylinder wall. 

 

Popped the piston to measure.  I bought them new less than 500 miles ago.

 

Top measured 3.325 and bottom measure 3.345.  20 thousands of an inch difference top to bottom?

 

Still hunting for the poor compression readings. 

Bores seem within spec and the bottom of the pistons(new) seem in spec, but the top of the pistons?

 

Ganna hang my shit out there flappin' in the wind, but who cares need to find out what went wrong.

 

Bore walls look kinda crap.  And I honed them.

 

 

I reckon the rod bearings look toast due to me not measuring using plastigage?  I think I got that lesson.

 

 

 

Less than 500 miles ago I honed cylinders. New pistons and rings and rod bearings on this motor. 

 

I think the bores are still measuring within spec. 

 

The only sure thing I can find I did wrong was not measuring using plastigage.

 

The top to bottom taper of the piston is an unknown to me?

 

Thanks kevin

[ggzilla]

Pistons are not supposed to be symmetrical.

Measure them at the places shown in the repair manual.

[datzenmike]

Narrower at top to allow for heat expansion.

 

Take the oversize pistons and bore this block out to 85.5mm

[atkinson40]

Narrower at top to allow for heat expansion.

 

Take the oversize pistons and bore this block out to 85.5mm

 

 

Thanks Mike and ggzilla.

 

Too late for rebore on the old block this go around. 

I've already installed the new engine while waiting for the rings.

 

 

I'm going to study the old engine and use it as a learning device.

I'd like to find out why the compression was bad.  More measuring.

 

 

When it comes time to rebuild again, I'll rebore the old one to 85.5 as Mike advised and get oversize pistons.

 

Thanks kevin

[ggzilla]

Why rebore the engine? Only do that if the bore is worn too much relative to the fixed piston size.

 

If you do decide to rebore, remember to get the oversize pistons FIRST so you can have the block bored to the closer side of the specifications. Closer tolerance = more HP and less wear.

[atkinson40]

Why rebore the engine? Only do that if the bore is worn too much relative to the fixed piston size.

 

If you do decide to rebore, remember to get the oversize pistons FIRST so you can have the block bored to the closer side of the specifications. Closer tolerance = more HP and less wear.

Thanks ggzilla,

 

I'm going to measure and measure and measure again.  I'd like to find the reason for poor compression.  If everything checks out, no rebore.  Thanks Kevin

[datzenmike]

I suggested re boring because don't you have a set of 85.5mm pistons in one of these L18s?

[atkinson40]

I suggested re boring because don't you have a set of 85.5mm pistons in one of these L18s?

Thanks Mike, Yes I do.  The JY motor(85.5) seemed OK so I just cleaned it up and kept the pistons with it.  When I removed the rings to clean the piston groves, I broke one. :blush:  So I needed to replace the rings.

 

The motor that came out with the poor compression(85 STD) I want to keep together and try to figure out what I did wrong when I rebuilt it.   So far my initial measurements don't present any obvious reasons.

 

I've almost got everything back together and ready to fire up......Maybe today.

 

 

I didn't pull or put back in this motor per suggested  forum wisdom. 

 

I unbolted the head and manifolds together and lifted them off and into the truck bed.

 

I then unbolted the tranny from the block and pulled the block.

 

Finally I pulled the tranny. 

 

Installation I bolted the tranny to the short block and installed them together.

 

Then I lowered the head/manifolds onto the block.

 

I realise I could have pulled them all as one, but I'm a puss. :blush:

 

Thanks kevin

[atkinson40]

Found a new toy at the swap meet I couldn't pass up. $25 B)   Upon return I began to button up the 620.

 

 

It was getting to be around 4PM.  Time for my daily bike ride.  I ain't too keen on riding the trails and streets in the dark after spending 3 days in intensive care with my brain bleeding after being hit by a truck. :crying:

 

But.... before taking off for the ride I was able to get her to crank over and start up.  She ran like crap.  Only sounded like a couple of cylinders hitting.  I turned her off and went for my ride.

 

When I returned there was enough light for me to set the pully to TDC and pull the dizzy cap to see it pointing to the #1 terminal.  Seems like I got the oil pump in OK. 

 

Later today I'll pull the VC and check the bottom to top end timing.  I thought I got that correct also.  The little tiny mark on the upper gear and the mark on the camshaft were lined up with the engine at TDC.  Maybe I got them off 180. :blush:   I dunno

 

The starter is giving me fits.  Before this last teardown it would intermitantly go click instead of turning over.  Now it seems to be doing the click almost allways, not letting me turn the truck over.  Is there a simple fix for this?  I could go to the JY and hope tp find one, or pull this one and have it rebuilt in Mexico.  Either would be cheaper than buying a new one. 

 

 

Thanks kevin

[ggzilla]

> Before this last teardown it would intermitantly go click instead of turning over. Now it seems to be doing the click almost allways, not letting me turn the truck over. Is there a simple fix for this?

 

Yes, easy fix. It doesn't always fix it, but it fixes the most common cause of these symptoms. And it is very easy to do, only takes a few minutes to try it. Clean the battery terminals and battery cables down to shiny, bright metal.

[atkinson40]

> Before this last teardown it would intermitantly go click instead of turning over. Now it seems to be doing the click almost allways, not letting me turn the truck over. Is there a simple fix for this?

 

Yes, easy fix. It doesn't always fix it, but it fixes the most common cause of these symptoms. And it is very easy to do, only takes a few minutes to try it. Clean the battery terminals and battery cables down to shiny, bright metal.

 

Thanks ggzilla

 

I went to the JY and picked up a couple of bolt tightening connectors and replaced the soldered ones that were on there.  No help, so I then removed the big connector from the starter and cleaned it.  Turns over like a champ now.  Thanks!

 

Now the timing issue:

 

Pulley set to the pointer.

 

 

 

Top end set to bottom end.

 

 

Dizzy rotor set to #1 terminal.

 

 

Evewrything should be OK...ready to go??  But nooooo it starts and kinda and runs like crap. :crying:

 

Here's the caveat that I'm not sure of.  The motor I put in had the timing indicator on the timing chain cover about 90 degrees advanced from where the old one is. 

 

 

I swapped the timing cover from the old motor because it had a new water pump.  Also the JY wanted an extra $25 for the pully so I'm using the old pulley and timing cover.

 

Berfore I put the head on I checked that the #1 piston was at TDC when the pointer was on the TDC mark on the pully.

 

For this to all be true, the old pulley must have had the TDC mark advanced about 90 degrees advanced from the marks on this pulley.??

 

Am I overlooking something obvious? :blush:   Thanks Kevin

[hobbes_the_cat]

Pulleys and timing markers should stay as a set as there were different timing marker locations through the years and applications and pulleys were notched to match that specific timing marker location. They can't be mixed and matched. I think that's where you problem lies.

 

Never mind I just re red your post. So you kept the old cover and pulley together? Shouldn't be a problem there unless they were mis matched to begin with.

[atkinson40]

Pulleys and timing markers should stay as a set as there were different timing marker locations through the years and applications and pulleys were notched to match that specific timing marker location. They can't be mixed and matched. I think that's where you problem lies.

 

Never mind I just re red your post. So you kept the old cover and pulley together? Shouldn't be a problem there unless they were mis matched to begin with.

 

 

Thanks Hobbes,

 

I kept the pully and timing marker/cover as a set.

 

I'm going to let my mind wander a bit and please anyone step in if I run amuck.

 

I think I remember seeing #1 and #4 pistons at the top when I had the marker/pulley set to TDC.

 

This means these two cylinders are in synch, but one in cumbustion and the other in exhaust modes??

 

I think I remember seeing #2 and #3 pistons at the bottom when I had the marker/pulley set to TDC.

 

This means these two cylinders are also in synch, but one in cumbustion and the other in exhaust modes??

 

A cylinder is firing every 180 degrees of revolution.  It takes 2 complete revlutions to complete the cycle??

 

I should be able to watch the cam lobs and see them follow the firing order of the cylinders.

 

I can pull the plugs and stick a screwdriver in the holes to follow the sequence between the top and bottom ends??

 

Thanks kevin

[atkinson40]

Revisited the static timing and was able to get her up and running well enough to hop out of the cab and check the timing with a light. 

 

Set it to 12BTDC.

 

Still runs rough. 

 

Things To Check:

 

When they rebuilt the head, they replaced the cam.  Did they use the right one?

 

I found a 90 degree fitting at the JY that fits in the engine vent. 

It doesn't have the little nipple that went to a rubber line that I believe I remember is the gas tank vapor recovery.

So I just ran a tube from the 90 up to the intake manifold.  Need to think if this is OK?

 

Plug wires have some green corrosion on the inserts that I need to clean or replace.

 

Clickety Click coming from the valves.  Need to revisit the lash adjustment.

 

Thanks kevin

[DanielC]

"It doesn't have the little nipple that went to a rubber line that I believe I remember is the gas tank vapor recovery.

So I just ran a tube from the 90 up to the intake manifold.  Need to think if this is OK?"

 

Probably not.  This puts engine manifold vacuum on your gas tank, and makes it hard for the fuel pump to draw fuel out of the tank.  It also creates a huge vacuum leak in the engine, making it run bad.  It is possible hooking up full manifold vacuum to the gas tank could cause it to collapse.

 

On a 521, with evaporative emissions controls, there is a flow valve with three ports.  One port goes to the small tube on the crankcase.  One port goes to the vapor separator tank, by the gas tank, and one port goes to the air cleaner. 

The evaporative system has the PCV valve between manifold vacuum, and the system.

[Stoffregen Motorsports]

I'm not sure you have your cam timing set properly. The dot on the top of the gear is the reference mark, not the "1" in the middle of the gear. That would look to be at least a tooth off.

[ggzilla]

> "It doesn't have the little nipple that went to a rubber line that I believe I remember is the gas tank vapor recovery.

>

> So I just ran a tube from the 90 up to the intake manifold. Need to think if this is OK?"

 

The L20B has a smaller outlet meant to go to the Charcoal Canister. It is vapor recovery but needs to be switched.

 

The 521 used the flow guide valve for vapor recovery.

[atkinson40]

I'm not sure you have your cam timing set properly. The dot on the top of the gear is the reference mark, not the "1" in the middle of the gear. That would look to be at least a tooth off.

 

I need to think.  I dug out an old image of what the cam/gear position looked like before the machine shop changed the cam.  Note the position of the lobs on the #1 cylinder.

 

 

This is how it is now set up after the machine shop changed the camshaft. Note the lobs are in the same position for the #1 cylinder, but the cam gear must now be set differently than before??

 

 

 

I dunno.  Need to think some more.  I thought the important part was the cam lobe position on the #1 cylinder when the #1 cylinder is at TDC.  I dunno.  Need to think.  Thanks kevin

[atkinson40]

This is what the old motor vent looked like.

 

 

The new vent pipe I found doesn't have the tiny 90 degree nipple.  So I just double the small hose back to the junction it came from for the interim so it's not just flappin' in the breeze. :blush: (Like my junk is most of the time)  I thought this was just the gas tank recovery and would not affect the engine until I could put it back when I found a way to "Tee" into the crankcase vent.

 

 

 

I just ran the crankcase vent directly to the intake manifold as shown below.

 

 

 

Hope my pictures are clearer than my description. B)

 

Thanks kevin

[ggzilla]

Naw, don't do that. You have effectively partially plugged the Tank vent.

 

Here's how it supposed to go. Use a T in the hose connected to the Block Breather, if the breather tube doesn't have a secondary vent.

[atkinson40]

Naw, don't do that. You have effectively partially plugged the Tank vent.

 

Here's how it supposed to go. Use a T in the hose connected to the Block Breather, if the breather tube doesn't have a secondary vent.

 

 

Thanks ggzilla.

 

I'll use a "Tee" like you suggested.  I need to find some hose that will handle the heat.

 

I don't see the liquid vapor separator it in the engine compartment. Maybe it was amputated by the PO??

 

 

I've also replaced the original air cleaner.  It rattled......bad.  And I couldn't see WTF around and under it.  I'll need to find out how to do w/o that hookup in the diagram you posted.  Thanks kevin

 

PS:  Is there any way to determine if the machine shop replaced the cam with the correct one from the image I posted?  Thanks kevin

[datzenmike]

You can't tell by eye about the lobes. Generally they are at 10 and 2 o'clock and only good enough to say it's on the compression stroke....

 

 

As long as you are absolutely, 100% sure that you are at TDC on #1 cylinder then the deciding factor of weather the cam is properly timed, is this picture below. The notch on the back of the cam sprocket must be below or just to the right. If it is it is timed correctly. If i is to the left you will have to block the chain, remove the sprocket and turn to the next number and instal. If you are on #3 there is no more adjustment left and the chain should be replaced.

[ggzilla]

tha's in the fuel tank.

[atkinson40]

No your L18 head (likely an A87) will be fine. Was there a head on this motor???? If JDM it may have had a closed chamber.

 

 

I'm trying to identify my head.  No A87 stamped between #1 &  #2 plug holes.

 

I can't find any marks on it anywhere except in the below image.  Its on the boss where the fuel pump mounts.

 

I used an inspection mirror to fid it and then flipped it in Photoshop so it would read right.

 

 

 

 

Here is an image of the bottom of the head before it was rebuilt. 

 

Is it closed or open chamber?? 

 

Doesn't seam like peanut from the other picture of peanut heads I've found??

 

 

 

 

Thanks kevin

[atkinson40]

I'm trying to identify my head.  No A87 stamped between #1 &  #2 plug holes.

 

Never mind.  When they rebuilt the head they painted over the A87.  :blush:  

 

Further interweb search told me it's also an open chamber. 

 

I'll be looking to snag a closed chamber at the JY if I can.

 

But first, I'm going to need to pull the timing chain cover to find out WTF I did wrong??

 

I removed the VC and found this. :blush:

 

 

Only thing I can think of is the tensioner is not working or getting stuck. 

 

This is what's causing the clackity clack noise.  If I bump the tensioner side it snaps tight on the drive side.

 

3 cars down, 1 PU to go.  I have to start painting the house after I get them all up and running.

 

I wonder if I'm subconsciously lagging here.  :angel:

 

On the bright side I found some buckets for $15 each at the JY today. B)

 

They need cleaning, but no rips or tears.

 

 

Well...I'll be comfortable, won't be able to go anywhere, but I'll be comfortable. :D

 

Thanks kevin