Ok,

I've got a motor that I'm planning on using for a swap.

I decided to attempt to use a MAC blow-by tester to determine if there was a lot fo blow-by... or if there was anything I should worry about.

I'm finding the #1 has 20 psi, #2 has 40 psi, #3 has 0 psi, #4 has 95 psi.

(That would translate to 80%, 60%, 100%, and 5% loss or blow-by.)

So the question is...

After a motor has been sitting for a while and is cold... is there a reason to suspect these reading are completely inaccurate?

Also, do I need to be putting oil in the cylinders to get a proper reading? If so... how much?

 

Ok...

*Update*

I was speaking with a mechanic friend and he told me to adjust the valves.

He also indicated that sometimes the valves, after sitting for a while, may have crud on them. Setting the piston to the lowest part of it's individual cycle a lightly tapping the adjustment screw will somethimes clear that crud.

Guess what... IT WORKED.

It was obvious that the problem were valves... as I rotated the motor and began the closed valves part of the cycle, you could painly hear when the valves were not seating. (Hiiiiiiisssssssss)

Once that was fixed I saw between 95-100 PSI with the leakdown tester in each cylinder!

Looks like the valves and the pistions / rings are all fine.

(That was my biggest concern with a used motor!)

Gerhard

 

good news :thumup:

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by spnbb2 &raquo;</TD></TR><TR><TD CLASS="quote">good news :thumup:</TD></TR></TABLE>

 

its also better to do a leak down test when teh motor is warmed up

 

The problem is that the motor is not in a car and can not be tested warm.

I never dreamed I'd get good blow-by numbers... I wanted to see consistancy...