Tight spot rotating engine

Lonnie

Lonnie

Horsepower Addict
Oct 18, 2007
323
0
16
Pittsburgh, PA
www.lonniesperformance.com
Murphys law is at it again.

I just noticed a tight spot while turning my engine over. I never noticed it before when I pulled the converter bolts. It is at #1 TDC, which is also TDC for #4. It happens with the timing marks 1/4" on either side of TDC.

I'm nervous now & have to find the problem.

I have the oil pan off & everything is nice inside. Everything moves freely & looks perfect. To diagnose it, I carefully wiggled rods #1 & 4 while rotating the engine (removed glow to be sure). The rods will move side to side freely, until just at TDC, where #4 rod appears to have some pressure on it. Something has to be on top of the piston. It does not lock up & will rotate through this tight spot, but I'm worried that something isn't right.

Through my entire engine swap ordeal, the intake had tape over the ports just to be sure. I also had it running before I took it apart. I'm wondering if piece of carbon could have flaked off a piston & be touching the head. It cannot be valvetrain related because it is the same every revolution. Applying air to the cylinder, everything seals well so no bent valves etc.

Has anyone experienced anything like this? How much piston-to-deck clearance do these engines normally have? Please give me some feedback before I'm forced to pull the head off tomorrow. I just cannot install it this way without being sure it is OK.

Thanks,
Lonnie
 
MaxFarmer

MaxFarmer

<--Heavy Smoker
Jan 22, 2007
1,251
0
36
45
Albion, Nebraska
Lonnie said:
Murphys law is at it again.

Has anyone experienced anything like this? How much piston-to-deck clearance do these engines normally have? Please give me some feedback before I'm forced to pull the head off tomorrow. I just cannot install it this way without being sure it is OK.

Thanks,
Lonnie
Click to expand...

I went and looked at some of my rebuild notes. The best I can help you with is piston protrusion. I think my tallest protrusion was .022"
The machine shop paper says: "check deck hieght @ 10.313" "piston protrusion as received: 1-018, 2-018, 3-020, 4-021, 5-020, 6-021, 7-018, 8-019"

I hope this may help you some. I know when I was turning my engine over to take out the TC bolts it got tight a couple of times but I just assumed that it was compression.

Thats about all I'm good for....:eek:
 
M

Mike

hmmm....
Feb 17, 2007
2,184
0
36
San Angelo, TX
This may be elementary, but have you eliminated the water pump as well as drive accessories as a possible problem? Accessories probably won't give you a consistent location as you have mentioned, but start with the easy and then go onto the rest. Good luck to ya Lonnie.
 
Last edited:
Lonnie

Lonnie

Horsepower Addict
Oct 18, 2007
323
0
16
Pittsburgh, PA
www.lonniesperformance.com
Currently the engine is stripped of all accessories.

The waterpump is still installed. Any idea how it is geared to the engine... meaning does it run 1:1 with the engine?

I pulled the injection pump to be sure as well.

I realze the piston is very close to the head surface & it would not take but a small particle to block the movement. With a .022 protrusion & a gasket that is (guessing here) .060, that means something .040 could lock up the motor. That is why I first suspected a piece of carbon.

I did not loosen the rockers, but I did verify clearance when closed. I figured a valve issue would only occur every other revolution.

I did blow compressed air in the glow plug opening, & in both int/exh ports to try to move anything in there with no luck. But I turned it back & forth probably 50 times so you would think it would have been squashed by now.

I would swear it is #4 piston, but anything is possible.

Lonnie
 
Last edited:
M

Mike

hmmm....
Feb 17, 2007
2,184
0
36
San Angelo, TX
Lonnie said:
Currently the engine is stripped of all accessories.

The waterpump is still installed. Any idea how it is geared to the engine... meaning does it run 1:1 with the engine?

I pulled the injection pump to be sure as well.

I realze the piston is very close to the head surface & it would not take but a small particle to block the movement. With a .022 protrusion & a gasket that is (guessing here) .060, that means something .040 could lock up the motor. That is why I first suspected a piece of carbon.

I did blow compressed air in the glow plug opening, & in both int/exh ports to try to move anything in there with no luck. But I turned it back & forth probably 50 times so you would think it would have been squashed by now.

I would swear it is #4 piston, but anything is possible.

Lonnie
Click to expand...

Could there be something in the oil pump? The oil pump is 1 to 1 ratio if I remember. As far as the water pump, I'm thinking it's 1 to 1 but really it's been too long. This is a long shot, but if you have a way to turn the engine over fast, you could see if you get a clunk or tapping noise. Have you eliminated the possibility of a dry cylinder? Maybe try squirting oil into the glow plug hole and see what you get. If it is carbon, try a solvent that will break down carbon and see what happens. Maybe a good carburetor cleaner. Sorry about calling you Steve earlier, was thinking one thing and saying another Lonnie. Just ask Dale and Nick how long it takes me to get names right lol.
 
MAXLLY

MAXLLY

No Lemming Here
Aug 15, 2007
1,063
0
0
San Diego
this is a good one. I wake up in the middle of the night sometimes wondering about stuff like this, it's like a nightmare cause you just don't know 100% for sure.

The gasket is only 030 max so the tolerance is tighter than mentioned earlier. Mike's click/tap/clunk idea is solid. I have used a 1/2 right angle drill attached to the crank looong time ago (cut a 1/2" extension down, square it up a little and chuck it), it has enough torque to turn it over and enough speed to get a noise, try the screwdriver trick to accentuate the noise. Check the top of the valve does it look good on that cylinder? Rarely, maybe a retainer dropped/slipped?

I tore mine down weeks ago, I can share the following. While turning over my motor to remove TC bolts i got the same sensation, like a 2 stroke with a broken ring hanging in the port. I got all the way down to rod/piston removal with the same sensation, all my rods/mains looked perfect???? I think it was a liquid static (don't know what else to call it) and bearing clearance. It just felt like a "hitch" a "hang-up" ya know?

I didn't find a thing wrong.
 
Lonnie

Lonnie

Horsepower Addict
Oct 18, 2007
323
0
16
Pittsburgh, PA
www.lonniesperformance.com
Thanks everyone for all the info.

I tried to see if it was the oil pump & water pump, but it is hard without taking the whole front of the engine apart. Oil pump gear appears to be half the size of the crank (looking up from the bottom). That would make it spin double engine speed.

The water pump may be 1:1 (based on a photo of the engine internals). All gears look clean.

I will try the oil and/or cleaner in the cylinder. I never thought about a dry cylinder... always figured it was lubed pretty well. It ran about 2 months ago.

I have some fogging oil, maybe that is worth a try.


I hear a small clunk when it binds. It seems to be #4, It only really binds when you stop at this point. If you spin it fast with a ratchet on the balancer, it turns past this point, but you deifinitely know it should not be this way.

I really hate to take the head off, but I would also hate to put everything back together only to find out something is really wrong... only to take it all back apart again. On the other hand, I hate to buy a bunch of bolts & gaskets for nothing. Even using it as a good excuse to buy head studs is hard to swallow for the $$ they want for those.

MAXLLY,
Knowing you had a similar issue & found nothing is reassuring, but still makes me wonder what it could be.

Thanks everyone for the insight.
Lonnie
 
M

Mike

hmmm....
Feb 17, 2007
2,184
0
36
San Angelo, TX
Lonnie said:
Thanks everyone for all the info.

I tried to see if it was the oil pump & water pump, but it is hard without taking the whole front of the engine apart. Oil pump gear appears to be half the size of the crank (looking up from the bottom). That would make it spin double engine speed.

The water pump may be 1:1 (based on a photo of the engine internals). All gears look clean.

I will try the oil and/or cleaner in the cylinder. I never thought about a dry cylinder... always figured it was lubed pretty well. It ran about 2 months ago.

I have some fogging oil, maybe that is worth a try.


I hear a small clunk when it binds. It seems to be #4, It only really binds when you stop at this point. If you spin it fast with a ratchet on the balancer, it turns past this point, but you deifinitely know it should not be this way.

I really hate to take the head off, but I would also hate to put everything back together only to find out something is really wrong... only to take it all back apart again. On the other hand, I hate to buy a bunch of bolts & gaskets for nothing. Even using it as a good excuse to buy head studs is hard to swallow for the $$ they want for those.

MAXLLY,
Knowing you had a similar issue & found nothing is reassuring, but still makes me wonder what it could be.

Thanks everyone for the insight.
Lonnie
Click to expand...

Good luck to ya Lonnie. It's been a while since I've messed with my innerds so I'm sorry for the lack of memory. Let us know what you come up with would ya? Thanks
 
Lonnie

Lonnie

Horsepower Addict
Oct 18, 2007
323
0
16
Pittsburgh, PA
www.lonniesperformance.com
Well,
I tried a little upper cylinder lube to see if there was a difference, but no change.

After some more hesitation, I decided to risk wasting money on bolts & gaskets & removed the head. I'm very glad I did. Inside (on #4 piston) was a small piece of metal (7/16" x 3/16" x 1/32" approx). Not sure where it came from as there was no noise when it ran & I taped off the intake ports when I took it apart, but who knows what happened when the original vehicle was in the accident. Piston & head only had a slight clean spot on them. Nothing was hurt at least.

Attached is a picture

smallmetal.jpg


Glad I found something. Now I need parts again. Been seeing the Chevy dealer too often lately. One of these years the engine will actually get installed.

Thanks for all of your help.
Lonnie
 
M

Mike

hmmm....
Feb 17, 2007
2,184
0
36
San Angelo, TX
Wow, no telling what that was originally. Thanks for keeping us posted. You'll be glad you tore into it now and not later when a rebuild would have been needed. Good for you.
 
MAXLLY

MAXLLY

No Lemming Here
Aug 15, 2007
1,063
0
0
San Diego
would be cool to have another angle... glow plug all wadded op from compression???? Piched between piston and head?
 
You must log in or register to reply here.
Top Bottom