My car is a 1967 MK1A, I've read all the articles on how to perform a compression test, however I'm new to this, and my Tiger, and I'm hoping someone out there will have some tips to help me out. Some articles say to shut off the fuel supply, if this is necessary, then how do you do this, disconnect the pump? Also any tips on reaching the spark plugs? I really appreciate the forum, thanks.
compression test
- Thread starter dwllacey
- Start date
TigerBlue
Gold forum user
- Messages
- 827
Fuel cut off.
Assuming your Tiger is carburetor equipped cutting fuel supply should be unnecessary.
But easy to do on a Tiger because of the electric fuel pump. Pull the ground lead on the pump. I for one and other Tiger owners have a switch on the circuit. Multiple purpose including anti theft.
Removing spark plugs? Too much for me 2nite but my favorite is # 8 through the hole in firewall.
Rick
Assuming your Tiger is carburetor equipped cutting fuel supply should be unnecessary.
But easy to do on a Tiger because of the electric fuel pump. Pull the ground lead on the pump. I for one and other Tiger owners have a switch on the circuit. Multiple purpose including anti theft.
Removing spark plugs? Too much for me 2nite but my favorite is # 8 through the hole in firewall.
Rick
Warren
Gold forum user
- Messages
- 3,872
Okay
I have always done comp. checks on cycles but is problematic as you should have throttle open and engine warm.
Firewall access is best left to those with a long socket you can put open end wrench on and do that from engine bay.
I think proper plug color tells a really good story too.
I guess you need remote starter switch or 3rd hand, nice heat resistant gloves and a good screw in gauge. I bought a Harbor freight one and it is okay for as many timed as i used it.
Most will say leak down test is the accurate way to go but I can't say.
Probably the reason to shut fuel supply is thru 8 tests opening and closing throttle to WFO
dumps unburned fuel thru engine and these cars as they were equipped had old paper air filters which smoldering is a problem it you get a backfire so also remove coil wire.
I have always done comp. checks on cycles but is problematic as you should have throttle open and engine warm.
Firewall access is best left to those with a long socket you can put open end wrench on and do that from engine bay.
I think proper plug color tells a really good story too.
I guess you need remote starter switch or 3rd hand, nice heat resistant gloves and a good screw in gauge. I bought a Harbor freight one and it is okay for as many timed as i used it.
Most will say leak down test is the accurate way to go but I can't say.
Probably the reason to shut fuel supply is thru 8 tests opening and closing throttle to WFO
dumps unburned fuel thru engine and these cars as they were equipped had old paper air filters which smoldering is a problem it you get a backfire so also remove coil wire.
Better yet, before you go to the trouble of doing a compression test, find someone who has an "old school" engine analysis/diagnostic scope and knows how to read and diagnose problems with it. An experienced user can diagnose a multitude of engine problems with one of these (including, but not limited to, compression problems).
TigerBlue
Gold forum user
- Messages
- 827
a nuther 2 cents
Open throttle: Before the test open the throttle and poke a screwdriver in there to block the primaries open. Wide open unnecessary just need to be open enough that the intake of air is not restricted when cranking on by the starter.
Bleed down testing is to diagnose what is wrong? What you are looking for in the cranking test is 8 cylinders each pretty much the same. No point in doing a bleed down except to diagnose whether it (the low pressure cylinder) has a valve that is burnt? or maybe a broken ring?
Rick
Open throttle: Before the test open the throttle and poke a screwdriver in there to block the primaries open. Wide open unnecessary just need to be open enough that the intake of air is not restricted when cranking on by the starter.
Bleed down testing is to diagnose what is wrong? What you are looking for in the cranking test is 8 cylinders each pretty much the same. No point in doing a bleed down except to diagnose whether it (the low pressure cylinder) has a valve that is burnt? or maybe a broken ring?
Rick