Compression Checking

[SRX7]

Can some fill me in on a step by step process on checking compression.
Thanks.

 

[daman]

Can some fill me in on a step by step process on checking compression.
Thanks.

This is how i do it,, others may do it different.

1-warm up motor to operating temp.(take for a little ride if you can)

2-pick a cyl. and pull the plug,,screw comp. tester in,, hold throttle wide open.

3-with BOTH hands,, give it a good hard 7 pulls.

4- put that plug back in and move to the next cyl. and repeat above steps.

Record each test,,leave each pulg in except the one your working on.

I usually do each cyl. twice just to make shure the reading's right
and make shure key is off....

 

[**sj**]

daman is right on...one additon....make sure the "throw" is the same length as your spark plug..also....IMHO...Snap On is the most accurate

 

[redsnake3]

the snap on tester my buddy has always reads about 25 lbs more than any other gauge. but yeah the steps are really good, its good to have two people to do this so one can hold the throttle and the gauge and the other pull with 2 hands.

 

[SRX7]

Thanks

 

[**sj**]

you WILL get wrong readings with a snap on or any other with the wrong length throw...measure the thread length....no need for two...use a rubber band and pin her to the bar...I even take a large band to hold the gauge in sight while I pull....make sure the key is out of the machine... pull until it stops climbing...like 8-10 pulls...
also...you can check leakdown letting it sit under compression..

 

[SRX7]

Do you get higher numbers with a cold engine or hot ? Thanks

 

[Mac]

Compression

Why leave the other two plugs in each cylinder? Why would this give inaccurate readings?

 

[2ooosrx]

There is absolutely no point in putting the plug back in. Take all of the plugs out, hold throttle wode open and pull, do this for each cylinder then put all of your plugs back in.

 

[**sj**]

warming the engine expands the rings and seals..the idea is to get what compression you have WHEN IT'S RUNNING RIGHT? not while it's sitting outside....
2000 srx is correct there is no reading advantage towards plugs in...but it will keep your engine bay cleaner!

 

[daman]

This is how i do it,, others may do it different.

^^^^^

 

[2ooosrx]

^^^^^

Wasn't going against you, just wanted you to know that you can save time.

 

[daman]

Wasn't going against you,

np

We all do things are own way for a reason!!!!

 

[SRX7]

warming the engine expands the rings and seals..the idea is to get what compression you have WHEN IT'S RUNNING RIGHT? not while it's sitting outside....
2000 srx is correct there is no reading advantage towards plugs in...but it will keep your engine bay cleaner!

I did them when it was cold ( not time to run it yet but will ) all 3 were 125 lbs right across cold.