Planning for The Worst - Compression Test Coming Soon
03-26-2004, 02:32 PM
#1
Le Mans Master
Thread Starter
Planning for The Worst - Compression Test Coming Soon
Y'all may have been following my continuing problems regarding oil consumption. I'm averaging about 1/2-3/4 quart every 250 miles. Not good...
I've done about all I can to rule out potential oil leaks (intake gasket replaced/glued, brand new cylinder heads, etc.). What remains is to test the rings. I'm in the process of purchasing a compression tester and will be performing both dry and wet tests very soon.
If I find that the rings did not 'seat' properly in the bores, the options I am considering include:
1. Remove the engine, tear it down, re-bore and re-hone and re-assemble with basic rebuild kit and moly rings. I'm guessing close to $750 in parts and labor (assuming I do all ripping, stripping, delivery/pickup for machining, re-assembly and re-installation).
2. Tear down, re-hone, re-assemble with basic rebuild kit and moly rings. Approx $350.
3. Put the short block in a corner and purchase a GM Goodwrench LM1 and combine with my top-end parts. Approx $1750 including shipping
4. Same as #3 but spring for the basic HO with Vortec heads. Approx $2000 including shipping.
5. Live with the oil consumption until I can afford a ZZ4 or equivalent with all of the goodies.
One factor I have to consider with the rebuild options is that I have a .020" overbore already. I am hoping that any cylinder work can be limited to a max of .030 overbore.
I welcome your thoughts. :seeya
I've done about all I can to rule out potential oil leaks (intake gasket replaced/glued, brand new cylinder heads, etc.). What remains is to test the rings. I'm in the process of purchasing a compression tester and will be performing both dry and wet tests very soon.
If I find that the rings did not 'seat' properly in the bores, the options I am considering include:
1. Remove the engine, tear it down, re-bore and re-hone and re-assemble with basic rebuild kit and moly rings. I'm guessing close to $750 in parts and labor (assuming I do all ripping, stripping, delivery/pickup for machining, re-assembly and re-installation).
2. Tear down, re-hone, re-assemble with basic rebuild kit and moly rings. Approx $350.
3. Put the short block in a corner and purchase a GM Goodwrench LM1 and combine with my top-end parts. Approx $1750 including shipping
4. Same as #3 but spring for the basic HO with Vortec heads. Approx $2000 including shipping.
5. Live with the oil consumption until I can afford a ZZ4 or equivalent with all of the goodies.
One factor I have to consider with the rebuild options is that I have a .020" overbore already. I am hoping that any cylinder work can be limited to a max of .030 overbore.
I welcome your thoughts. :seeya
03-26-2004, 03:09 PM
#2
Race Director
Re: Planning for The Worst - Compression Test Coming Soon (TedH)
Rather than option #3, I'd suggest ordering a ZZ4 shortblock and picking up a new roller cam comparable in duration to the cam you have now. Would probably end up just slightly more expensive, but you'd have a roller valvetrain and better rear main. Also, better pistons and crank.
You'd need to get a new cam and new flexplate/flywheel.
http://www.sallee-chevrolet.com/Chev...ine_Block.html
-Steve
Although, at $2100 it was more expensive than I'd thought...
[Modified by Pacin'California, 12:12 PM 3/26/2004]
[Modified by Pacin'California, 12:21 PM 3/26/2004]
You'd need to get a new cam and new flexplate/flywheel.
http://www.sallee-chevrolet.com/Chev...ine_Block.html
-Steve
Although, at $2100 it was more expensive than I'd thought...
[Modified by Pacin'California, 12:12 PM 3/26/2004]
[Modified by Pacin'California, 12:21 PM 3/26/2004]
03-26-2004, 11:20 PM
#3
Re: Planning for The Worst - Compression Test Coming Soon (TedH)
Ted:
I haven't kept up on all your posts so I may ask some questions that you already answered.
Was all the motor work done at the same time? (bottem end rebiuld and new heads?) Or were they done seperately? Did you have the oil consumption problem right from the start or is it getting worse?
In order to use that amount of oil and be caused by the rings it would have to be a broken oil ring or an overlapped oil ring expander during intallation. This type of problem will not show up with either a compression test or a leakdown test. Both those tests will only show the condition of the top compression ring.
One other thing comes to mind is those heads have screw in studs. The threads for the intake rocker studs go completely into the intake port. If sealer was not used on the rocker studs they will suck oil into the intake port.
I haven't kept up on all your posts so I may ask some questions that you already answered.
Was all the motor work done at the same time? (bottem end rebiuld and new heads?) Or were they done seperately? Did you have the oil consumption problem right from the start or is it getting worse?
In order to use that amount of oil and be caused by the rings it would have to be a broken oil ring or an overlapped oil ring expander during intallation. This type of problem will not show up with either a compression test or a leakdown test. Both those tests will only show the condition of the top compression ring.
One other thing comes to mind is those heads have screw in studs. The threads for the intake rocker studs go completely into the intake port. If sealer was not used on the rocker studs they will suck oil into the intake port.
03-27-2004, 02:03 PM
#4
Le Mans Master
Thread Starter
Re: Planning for The Worst - Compression Test Coming Soon (Pete79L82)
Pete,
Good questions. The engine was rebuilt back in 1999. The entire top end (heads, intake, distrib, exhaust, etc.) came along between then and 2003. The oil consumption/leakage was a problem from the day I bought the car but from different problems (bad oil pan threads, and age of seals, gaskets, valves and rings being the dominant problem until the rebuild). With my rebuild, I had hoped to solve the oil consumption problem with intro of a set of rebuilt '882' heads in addition to a rebuild kit including all of the typical goodies to rebuild the shortblock. The engine continued to consume oil so I assumed the '882's were a problem. I wanted more performance and stepped up to the DART heads in 2002. Oil consumption continued but at what appeared to be a slowed pace. As you can probably see, I was treating the symptoms and not the problem. A mechanic performed the rebuild in 1999 and I assumed he properly installed the rings. If not, then I have a low-cost tear-down ahead of me to resolve the problem if it proves to be mis-installed rings. Power is great so I am assuming the rings are not broken or damaged and the pistons are not damaged.
Good questions. The engine was rebuilt back in 1999. The entire top end (heads, intake, distrib, exhaust, etc.) came along between then and 2003. The oil consumption/leakage was a problem from the day I bought the car but from different problems (bad oil pan threads, and age of seals, gaskets, valves and rings being the dominant problem until the rebuild). With my rebuild, I had hoped to solve the oil consumption problem with intro of a set of rebuilt '882' heads in addition to a rebuild kit including all of the typical goodies to rebuild the shortblock. The engine continued to consume oil so I assumed the '882's were a problem. I wanted more performance and stepped up to the DART heads in 2002. Oil consumption continued but at what appeared to be a slowed pace. As you can probably see, I was treating the symptoms and not the problem. A mechanic performed the rebuild in 1999 and I assumed he properly installed the rings. If not, then I have a low-cost tear-down ahead of me to resolve the problem if it proves to be mis-installed rings. Power is great so I am assuming the rings are not broken or damaged and the pistons are not damaged.
03-28-2004, 06:52 PM
#6
Melting Slicks
Member Since: Jan 2003
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Re: Planning for The Worst - Compression Test Coming Soon (Master Ho)
On my 69, I had a blown piston that only had about 15 - 20 pounds with a compression check. I replaced the piston, honed the cylinder and the compression was back to 130 lbs if I remember correctly. She still burned some oil so I had the heads done. I also re-did all of the rings on all pistons and that cured my problem of oil burning. (connecting rods bearings replaced when I removed the pistons as well) All the honing and ring replacement was done with the engine in the car. Cost? I can't remember the cost for the heads to be done (I replaced the valves and seals myself) but I think total cost wasn't more than $300...
No reason to replace the engine unless it needs bored out. I would say that if the engine was rebuilt, then there might be a possibilty that the rings did not seat correctly.
Also, I believe if any spark plugs are oily when you pull them I would say you are losing oil in that cylinder. I would check the plugs and then at the same time, do the compression check. That should determine the condition of the cylinders...
I am no mechanic by far but if I can do it, anyone can!!
Just my two cents worth!!!
No reason to replace the engine unless it needs bored out. I would say that if the engine was rebuilt, then there might be a possibilty that the rings did not seat correctly.
Also, I believe if any spark plugs are oily when you pull them I would say you are losing oil in that cylinder. I would check the plugs and then at the same time, do the compression check. That should determine the condition of the cylinders...
I am no mechanic by far but if I can do it, anyone can!!
Just my two cents worth!!!