Leak Down Test

[hgray14]

Does anyone have good instructions on how to do a leak down test for a Volvo 850? I have a '93 850 GLT, a '95 850 Turbo and a '95 850 T-5R that I want to run the test on.

thanks

[mojojo]

Google.

http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=how+to+perform+leak+down+test

Remember to perform a compression test as well, for a good showing of the over all shape of the engine.

[hgray14]

Google.

http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=how+to+perform+leak+down+test

Remember to perform a compression test as well, for a good showing of the over all shape of the engine.

Thanks. I will do a compression test too.

So, nothing special for our cars.

One thing I don't know is how to find TDC on these engines. Are there marks to help me or do I just get out the old flashlight and stare down the hole until I see the top of the piston?

Thanks again

[Rsterns]

Thanks. I will do a compression test too.

So, nothing special for our cars.

One thing I don't know is how to find TDC on these engines. Are there marks to help me or do I just get out the old flashlight and stare down the hole until I see the top of the piston?

Thanks again

You need to remove the front cover, here is TDC for the Crank as well as the cams....

The notches on the gears line up with the notches in the cover...

[whoa]

That's close to (not exactly, I think) TDC for cylinder #1. Anyway, you are supposed to bring each cylinder, not just #1, to its TDC for leak-down testing (because that's where the most cylinder wear would be, if there is any). So stick something into the cylinder that's 10 inches long or so; I used a long cable tie, and watch it while manually cranking. You should wiggle the crank back and forth after pressurizing to be sure the rings seat properly.

[hgray14]

So the small notch on the right gear at about the 10 o'clock position is the one you are referring to? and that should line up with the notches just above that right gear on the plastic cover?

That is TDC for cylinder 1, right? How do I find it for the other cylinders?

sorry for all the questions but I have never done anything that required TDC for anything other than the 1st cylinder.

thanks again

[mojojo]

Thanks. I will do a compression test too.

So, nothing special for our cars.

One thing I don't know is how to find TDC on these engines. Are there marks to help me or do I just get out the old flashlight and stare down the hole until I see the top of the piston?

Thanks again

You don't have to remove the front cover, especially if you have a friend over that can help with the test.

to find your compression stroke (and begin the leak down test), you will remove the spark plug (removing all of them helps in turning over the engine-even for the cylinders you're not testing at that point), and rotate the engine in the normal running direction, then place your finger over the plug hole and when you feel compression building (pushing your finger off), rotate slowly until the pressure eases off. Next install your plug adapter and begin the test. If the engine moves because you're not at TDCC (which is probably going to happen at some point), have your buddy old the crank still with a breaker bar and socket on the crank pulley bolt.

It doesn't matter where the piston is in the cylinder, as long as you're on the compression stroke, for you to get accurate readings.

It makes life easier removing the front cover, but it's not always easy with the engine in the car, and is really unnecessary and simply time consuming.

That's close to (not exactly, I think) TDC for cylinder #1. Anyway, you are supposed to bring each cylinder, not just #1, to its TDC for leak-down testing (because that's where the most cylinder wear would be, if there is any). So stick something into the cylinder that's 10 inches long or so; I used a long cable tie, and watch it while manually cranking. You should wiggle the crank back and forth after pressurizing to be sure the rings seat properly.

Never. Never. Never, put anything in to an engine to determine TDC. Period.

[Rsterns]

You don't have to remove the front cover, especially if you have a friend over that can help with the test.

to find your compression stroke (and begin the leak down test), you will remove the spark plug (removing all of them helps in turning over the engine-even for the cylinders you're not testing at that point), and rotate the engine in the normal running direction, then place your finger over the plug hole and when you feel compression building (pushing your finger off), rotate slowly until the pressure eases off. Next install your plug adapter and begin the test. If the engine moves because you're not at TDCC (which is probably going to happen at some point), have your buddy old the crank still with a breaker bar and socket on the crank pulley bolt.

It doesn't matter where the piston is in the cylinder, as long as you're on the compression stroke, for you to get accurate readings.

It makes life easier removing the front cover, but it's not always easy with the engine in the car, and is really unnecessary and simply time consuming.

Never. Never. Never, put anything in to an engine to determine TDC. Period.

You must have some long fingers if your going to plug the spark plug hole on these motors! What makes it worse, is you should perform this test on a motor that's all warmed up. The rest of what you state is accurate, however in answer to the original question of indicators for TDC, the photo's are accurate and you do need to remove the cover to see them.

[mojojo]

You must have some long fingers if your going to plug the spark plug hole on these motors! What makes it worse, is you should perform this test on a motor that's all warmed up. The rest of what you state is accurate, however in answer to the original question of indicators for TDC, the photo's are accurate and you do need to remove the cover to see them.

...Skip the fingers, place the palm of your hand over the plug hole in the valve cover, and feel for compression.

For holes that are long away, I use the plug adapter I'm going to use when performing the leak down test, and hold my thumb over the end waiting for compression to build.

[whoa]

I live dangerously, I guess. I suppose there must be lots of reports on-line about people damaging their pistons by having the ends of drinking straws and cable ties resting on them. I've missed them so far.

[hgray14]

It must be those diamond tipped zip-ties! LOL

but seriously, I can see his point. The last thing you want is to loose something down in there. I like the idea of a really long cable tie but then again, since the adapter is going into the hole anyways I can do the "finger" method too.

Thanks to everyone for your help. I just got my leak-down tester from Harbor Freight and so now I chomping at the bit to test all my cars. I usually do an annual compression test but this will add a whole other level of comfort to my yearly maintanance records.