Running Rough

[Gene Fiore]

Just got the cylinder head back from my machinest...it's in great shape. Motor coming out this Saturday morning...

 

[MPGmustang]

hey gene, why is the engine coming out? can't you take piston 1 out in the car?

 

[Gene Fiore]

hey gene, why is the engine coming out? can't you take piston 1 out in the car?

I hate working under a car...that's the reason. Plus if it needs anything else I'm ready for it.

 

[woodbutcher]

Hi Gene.Sorry to hear about your problems.I guess it happens to all of us at one time or another.Hope its something simple(read cheap)to fix.
Good luck.Have fun.Be safe.
Leo

 

[69.5Mav]

The number 1 cylinder is only reading 60-65 while all the others are 155-160.

I am going to sound a cationary note here.

In the '70s My first car was a 1961 chevy. It had a 235 CI inline six most like the ford 240/300. It was a massive big heavy block that I had had rebuilt twice by a shade tree mechanic. Near the end it was burning 1 Qt of oil every 50 miles, must have looked like a mosquito fogger going down the street, but I was yung and poor.

Now that I've set the stage I tested the compression on that engine numerous times and got the following numbers consistantly regardless of the gage I used.

1 119
2 125
3 130
4 135
5 130
6 125

The book called for 135 for this engine.

When the engine through the number four rod bearing I disasembled the engine and found the following.

Number 1 piston was missing part of the top of the piston as well as most of the number 1 ring, the rest of the ring land was filled with a black substance. The second ring was broken.
All the rest of the rings were broken except four the number four cylinder which had the blown rod bearing.

The upshot here is that I think you have something else going on here other then a broken ring.

I would check the block for flatness before I pull it.

So that’s my 2cents. It’s cheap and easy to do and you can do before you pull the engine this coming weekend with out having to crawl under the car.

 

[Gene Fiore]

The number 1 cylinder is only reading 60-65 while all the others are 155-160.

I am going to sound a cationary note here.

In the '70s My first car was a 1961 chevy. It had a 235 CI inline six most like the ford 240/300. It was a massive big heavy block that I had had rebuilt twice by a shade tree mechanic. Near the end it was burning 1 Qt of oil every 50 miles, must have looked like a mosquito fogger going down the street, but I was yung and poor.

Now that I've set the stage I tested the compression on that engine numerous times and got the following numbers consistantly regardless of the gage I used.

1 119
2 125
3 130
4 135
5 130
6 125

The book called for 135 for this engine.

When the engine through the number four rod bearing I disasembled the engine and found the following.

Number 1 piston was missing part of the top of the piston as well as most of the number 1 ring, the rest of the ring land was filled with a black substance. The second ring was broken.
All the rest of the rings were broken except four the number four cylinder which had the blown rod bearing.

The upshot here is that I think you have something else going on here other then a broken ring.

I would check the block for flatness before I pull it.

So that’s my 2cents. It’s cheap and easy to do and you can do before you pull the engine this coming weekend with out having to crawl under the car.

Thanks for your input...this block was decked to insure flatness when I built it 2000 miles ago so I would hope that it is still flat but it's worth checking.

 

[MPGmustang]

I hate working under a car....

then WHY do you have an old car??? :rolflmao: lol

alright, sounds good. IIRC I thought you were runnign rich? would rich conditions make you loose a ring? I guess it's possible as you run it all out and not as a daily driver.

 

[Gene Fiore]

I hate working under a car....

then WHY do you have an old car??? :rolflmao: lol

alright, sounds good. IIRC I thought you were runnign rich? would rich conditions make you loose a ring? I guess it's possible as you run it all out and not as a daily driver.

I was running rich but I think in my efforts to lean it out I ended up with a too lean condition on number 1 and lost the ring...I'll know for sure Saturday.

 

[mugsy]

I finally got the head off last night and was hoping to see signs of a blown head gasket on the pushrod side of the motor...nope. Head gasket looks good but completely covered with oil. The previous head gasket was in the same condition...covered with oil. Not sure what to think of that. Also this time the top of every piston is covered with oil. Could doing the compression test caused oil to get up on top of the pistons? One good thing so far is I turned the motor over to get the number one piston at the bottom of the stroke and the cylinder looks perfect...no scoring or any signs of carnage. Just to make certain the head is ok I am going to take it to my machinest to have him check it out. Assuming that is ok then the next step is pull the motor and take the number one piston out and see what's going on there. I hate it when things break!

Well if the rings or piston was bad in #1 it was pressurizing the crankcase. The oil vapor would have gone pretty much everywhere including the intake if you were running a PVC system. The PVC was sucking the oil vapor right into the intake and then into each cylinder. That's my guess as to how the oil got on top of each piston.

 

[Gene Fiore]

Well if the rings or piston was bad in #1 it was pressurizing the crankcase. The oil vapor would have gone pretty much everywhere including the intake if you were running a PVC system. The PVC was sucking the oil vapor right into the intake and then into each cylinder. That's my guess as to how the oil got on top of each piston.

Agreed!! And I was running a PCV system but the valve cover has no baffles so I was just running baffled grommets...adding to the issue.

 

[wsa111]

Gene, mount the pcv 4" above the baffled grommet using a hose so no oil will get close to the pcv valve.
Oil in a fuel mixture will lower the octane rating which could aggrivate a preignition condition.
However in your case its a lean mixture which fried #1 hole.
Did you get the engine apart to access the damage???
I hope the cylinder walls are not scored. Good luck, Bill

 

[Gene Fiore]

Gene, mount the pcv 4" above the baffled grommet using a hose so no oil will get close to the pcv valve.
Oil in a fuel mixture will lower the octane rating which could aggrivate a preignition condition.
However in your case its a lean mixture which fried #1 hole.
Did you get the engine apart to access the damage???
I hope the cylinder walls are not scored. Good luck, Bill

Actually I was thinking of eliminating the pcv and just go with two breathers at either end of the valve cover. I will have the engine out this Saturday morning so I will know soon. The head is already off and the cylinder walls look fine.

 

[mugsy]

Just my $0.02 but baffles won't help if the crankcase was being pressurized. The hot combustion gasses were getting into the crankcase and the oil vapor was going to go all over the place regardless of PCV location.

Good luck on the detective work and re-build and let us know what you find!

 

[jahearne]

Best of luck, Gene! got my fingers crossed

 

[Gene Fiore]

I pulled the engine this morning and got the number one piston out. The ring land is broken. The good news is I have an extra piston and rings left over from the original build.

 

[bubba22349]

How much ring end gap do you have?

 

[69.5Mav]

Pictures Please.

 

[Gene Fiore]

It's a little hard to tell...but there is a section of the ring land missing from this side of the piston...the pieces are pictured below.

 

[69.5Mav]

Good call. That piston deffinetely needed replacing.

It looks like both rings were affected, correct?

 

[MPGmustang]

since you have it out, are you going to check all the pistons?