Compression Tester

[kmon]

Hey,

A compression is pretty easy to do. First you need a *caugh* compression testor. Then take the coil off the distributor, and pull the spark plugs one at a time. Place the testor in where the spark plug was and have a friend crank the car over (2 or 3 times is fine). The tester will then read the highest pressure. Repeat for the other three plugs. Your numbers should be hovering right around 100, if you see 1 plug with a much lower number than the rest (say 10 points or more lower), retest it, if you sill have a low number you should look into a rebulid (new rings, but while your in there might as well clean everything up). Just a note, ths test does give you result a little lower than 'true' compression by 10-20 points. Also elevation effects the numbers (since you at see lvl you have no worries). I'm at 7200 ft so i had to take that into account. Also when you have the plugs out take a good look at them. Do they look they have gotten hot (running lean) or have build up on them (too rich or buning oil). This is a good 'first step'. If the car will fire drive it around, how are the power transitions? If it feels strong all the way through the power band, you have a very rare find. I havent spent much time in 'opel' country, but here in wyoming its darn hard to find opels. Most 'older' folk (no offense intented for anyone), recognize the car. But my firends scratch there heads when the see the car. Its does turn heads, and I love it to death. It has become my daily driver, and boy what a car to crusie in. OGTS has a lot of great guys working there. If have an extra day, I would recommend a trip, just to look around if nothing else. After you inital buy the car, you will see just how much you can put it. The list is endless. Just keep posting your questions, and make sure to post some pics when you find the right car

[ghouliegirl]

Kmon, thank you so much for that description of compression testing. Let me ask a couple'a stupid questions now...

How much does a compression tester cost? Where do I find one? Is it specific to the car (Opel) or can I go to a general parts store and get a generic tester that will work on any car?

Do the manuals have a description of compression testing, including removing the coil and spark plugs and what tools are needed to do these things? I have absolutely no experience with these things (though I do, at least, know where the plugs are on my jeep, and I can change my own oil...)

At what point would you consider the Opel a "bad buy" for someone like me -- if one plug has low numbers, or all four?

Yeah, I'm really going to try to get to OGTS, probably one day next week. I'm still a ways away from getting my first Opel, but I can learn a ton from being here and there in the meantime...

And Kyle, I would *love* to go to the picnic but I just don't think I'll be able to get down there -- school finals will be coming up, so...

Are there any events in northern California?

Nathan
Martinez, CA

[ghouliegirl]

P.S. - do you think a compression tester is a good thing to have on hand/a worthy investment? From what I am seeing online (initial search) is that they're just under $200.00...

Thanks!
Nathan

[ghouliegirl]

Ack! I just checked Ebay -- *much* cheaper, but I have no idea what they all are, or what the differences are. Can anyone offer some advice?

If I get a compression tester, what would be a decent one for me, and where should I get it?

Remember, you told me to ask questions, so it's all your fault! <grin>
Nathan

[jordan]

auto zone has one for $30 brand new and it a pretty good one, its analog (meaning that it has a needle instead of digital) they work great. and then they get fancier, there are some that have LED screen and can display the compression of 10 cylinders, they can find the highest compression, the lowest, and the average of all cylinders but the only catch is they are $700! (truely a tim allen tool )

[kmon]

Do get a tester or not? I always like to have one around, its one of those odd tools that you when you need it you wish you had it. And like has been suggested you can pick one up pretty cheap. As far as 'analog' vs 'digital' I'm still kind of old school with that. The led testers are quite expensive to get a good one. I would look around at some of your local pawn shops for a tester, they are always laying around. Dont pay much over a $100. You should be able to get one for less, but if you spy one that looks good to you grab it! I have three or four laying around, and they all are different types. Each tester was there own neck, some have hose attachments, etc. My favortive compression testor (boy that sounds geeky) is one with blunt tip that you just shove in and hold pressure against it. You really don't need one with memory or anything like that, just pick up one that looks sturdy...is easy to use, read, and the 'dump' button is in a logical place (some of them have really odd designs). So again, the choice is up to you, but I would pick one up just to have it.


.....as a side note, there really arent any stupid questions. Everyone starts from somewhere, and I'm always asking questions as well. If you ever have a question, please just ask it

[Leifer]

Nathan, if you spend more than $50 on a comp tester I think you're considering a career in auto mechanics. My dad has one about 25 yrs. old and it works fine (didn't pay $50, but money was worth more then).
Memory is overrated too. If you have a pencil and scratch paper you're good to go. I prefer the ones that thread into the plug so you have both hands free; you may need an adapter to make everything fit up right.
I have other comments, but they're not related to this thread. I'm going back to your original thread.