Practical compression test question

Worship79

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Don't know if this is the exact right section and sorry for the beginner question, but here we go anyway:

I have headers and wonder hot to remove the sparkplugs and spark plug boots after having warmed up the engine for a compression test?

Now I have to loosen the header bolts and lift the header to get my socket over the nr. 1 and nr. 8 plugs. With a hot engine, I'll have no skin left :twitch:

I used a standard 16mm (5/8") plugsocket, are there other options perhaps? Tried a wrench, but no sigar due to the reces the plugs are in.

Thanks!
 
Deep reach box end wrench, 16mm usually. No need to remove headers (assuming hooker sidemounts?)
 
Sidemounts indeed, sorry for forgetting to mention that. I used the socket below today, but had to loosen headers bolts to slip it over the nr. 1 and 8 plugs. I'm guessing you mean another type of socket?

n-0101.jpg


Will a boot puller do me any good, considering the hot headers?
 
I have to use a wrench like that to reach 4 plugs,and also another little tip that might help you,get yourself a length of vacume hose 8-9" long that will fit snug over the plug tip after you broke the plug loose with a wrench,the hose is flexible and will get your hands out in the open to finish getting the plug out. I also like to use it to install the plugs,with the headers and tight area it makes it easy to install the plugs also with the Alum heads it will prevent a cross thread.
 
@kwplot34: thanks for the hose tip!

I was told I could do the compression test with a cold engine too. True, false or non-useful results when doing so?
 
Yes, you can do it on a cold engine, however the pressure results will be lower as the seal is less perfect. It will still give you a good indication
 
Finally got around to compression testing, did it on a cold engine. I think I can conclude all is well inside the engine?

Cyl. PSI
1 - 155
3 - 155
5 - 160
7 - 160

2 - 160
4 - 155
6 - 160
8 - 160

The hella tester has both bar and psi on it, but the scale was only in 5 psi at a time (150, 155, 160, etc.), but I'm guessing these readings are good enough.
 
In addition to the final "total" compression, how it gets there is also a tool for evaluating the health. If it jumps in 10 psi increments and you just keep cranking until you get to 150, i'd say it's pretty sick.

If the first stroke does 60-80 and the 5th stroke is 160, then it's pretty good.

Another thing would be a leak down test- both valves closed, piston at TDC and give it some air- listen at the intake, exhaust, and crankcase for air leaking.
They do make a gauge set you can do the leak down test with- one gauge shows inlet pressure and the other shows how much the cylinder is holding. Gives you a feel for percentage of leakage.

You could give each cylinder a shot of oil and see how much improvement you get. With the numbers you posted it'd kind of be a waste of time IMHO..
 
Finally got around to compression testing, did it on a cold engine. I think I can conclude all is well inside the engine?

Cyl. PSI
1 - 155
3 - 155
5 - 160
7 - 160

2 - 160
4 - 155
6 - 160
8 - 160

The hella tester has both bar and psi on it, but the scale was only in 5 psi at a time (150, 155, 160, etc.), but I'm guessing these readings are good enough.


Actually, it looks good. :drink:
 
If the first stroke does 60-80 and the 5th stroke is 160, then it's pretty good.

That's how it went.

Another thing would be a leak down test

I don't have the tools for that, but I'm considering asking my garage to do that.

You could give each cylinder a shot of oil and see how much improvement you get. With the numbers you posted it'd kind of be a waste of time IMHO..

This I can and will do this evening or weekend. I don't think my test was a waste of time though. I know compression is ok, as are my gaskets and if not for anything else I learned how to do it (first time) :)

Now... what is the correct/best/most pratical way to measure valve lift? I can borrow a good micrometre and magnetic foot from a friend. And then?
 
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Finally got around to compression testing, did it on a cold engine. I think I can conclude all is well inside the engine?

Cyl. PSI
1 - 155
3 - 155
5 - 160
7 - 160

2 - 160
4 - 155
6 - 160
8 - 160

The hella tester has both bar and psi on it, but the scale was only in 5 psi at a time (150, 155, 160, etc.), but I'm guessing these readings are good enough.


I assume this was with a cold engine in which case those are good readings, they would be in the 176-190 range hot for your engine (Lm-1 eq)
 
first DON,T PAY FOR IT :down: ...DO IT YOURSELF!!! :thumbsup:
IT WILL COST LESS EVEN AFTER PAYING FOR THE TOOLS AT MOST GARAGES.

youll find that youll gain basic skills, own new tools and PAY LESS MONEY
:thumbsup:




read this

http://www.xs11.com/tips/misc/misc3.shtml



http://www.tavia.com/cat8.html#3



http://www.motorcycleproject.com/motorcycle/text/leakdown.html

http://www.xs11.com/tips/misc/misc3.shtml

TAV-8016.JPG

http://goodvibesracing.com/Leakdown%20Tester.htm
1) For most accurate results, engine should be up to operating temperture.

2) Remove all spark plugs.

3) Rotate crankshaft until piston being tested is at top dead center of compression stroke.

4) Screw the spark plug adaptor hose into spark plug hole making the sure the o-ring is seated properly.

5) Connect the spark plug adaptor hose to the coupler of the leakdown tester.

6) Connect leakdown tester to a good source of compressed air, preferably a filtered and water trapped source.

7) Adjust the regulator on the leakdown tester so the the LEFT HAND GAUGE indicates at least 10 pounds less than your sorce pressure. The leakdown percentage conversion table shown below is based on regulated pressures of 100, 90, or 75 psi.

8) Read the RIGHT HAND GAUGE (differential gauge), then look up gauge reading on the conversion table below to get actual leakdown percentage. After noting percentage of leakage, turn the regulator knob counter-clockwise to relieve the pressure. This reduces the shock to the gauges. If you ever get an unrealistically low pressure reading on the right hand gauge, there is a finite possibilty that something is blocking the small orfice located within the hex tube located between the regulator and the main body of the leakdown tester.

9)To remove any obstruction that may be lodged in the metering orfice, unscrew the hose coupling assembly from the aluminum body. Ultilizing a 1" wrench, remove the knob assembly from the regulator. Blow compressed air in the opposite direction (from the coupling end) to clear the orfice. Re-assemble the regulator and the coupling.

NOTE: DO NOT ATTEMPT TO REMOVE THE BRASS HEX NIPPLE BETWEEN THE REGULATOR AND THE ALUMINUM BODY. DAMAGE MAY RESULT.

SUM-900010-TL.jpg


http://www.maximausa.com/technical/leaktest.html

http://www.meyerracingonline.com/leak.html

http://www.compressionking.com/leakdown.htm

http://www.lcengineering.com/TechNotes/TechNote47.htm
 
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