Cylinder compression tester

[TRevs]

The cars I drive most are high mileage (181k 4.0L wrangler, 268k honda), and I’d like to buy a compression test tool, especially on the Civic because its performance/ fuel economy have dropped slowly over years and now Im having moderate oil consumption.

Are there any recommendations? Home garage DIY level. Are products in the $50-100 range any better than the <$50 ones?

 

[LukesfirstJeep]

I have a vintage Craftsman that I like. The thing I've learned over the years is compression testers are better for comparison vs absolute pressure. My gauge may read 150 psi, while somebody else's reads 160 or 140. Your first reading will be your baseline and future readings will be compared to that. Unless the unit comes with some calibration certificate, I don't think higher priced units are more accurate, just more durable.

What is the thread pitch of your spark plugs? My tester came with a single hose with several thread adapters for the end. This works on most engines, but I've purchased several different hoses with different threads for certain vehicles.

I sourced one hose from Snap-On, but that was 1989.

 

[TRevs]

I don’t know the thread pitch but I imagine it’s different between a Honda aluminum K20 and a Jeep 4.0, so I figured I’d need a tester with adapters.

 

[sab]

I have a vintage Craftsman that I like.

Me, too!

The thing I've learned over the years is compression testers are better for comparison vs absolute pressure...Your first reading will be your baseline and future readings will be compared to that.

Agreed. In fact, I used my leak down gauges (OTC 5609) more often than the compression gauge. I find it to be a much more useful diagnostic tool.

Unless the unit comes with some calibration certificate, I don't think higher priced units are more accurate, just more durable.

Agreed, once again.

What is the thread pitch of your spark plugs? My tester came with a single hose with several thread adapters for the end. This works on most engines, but I've purchased several different hoses with different threads for certain vehicles.

The problem with the older kits, like the Craftsman we both own, is that there have been several new spark plugs come into use (mostly smaller, since engines are smaller nowadays) since those kits were purchased. Most of the compression testers currently on the market have adapters for today's common spark plugs.

The cars I drive most are high mileage (181k 4.0L wrangler, 268k honda)

I, too, drive high mileage cars. My daily driver is a 26-year-old Subaru with 395k on it!

Are there any recommendations? Home garage DIY level. Are products in the $50-100 range any better than the <$50 ones?

If I had to do it over again, I'd buy the leak down gauges first. However, you need to have a compressed air supply to use it. If you don't have that, it's probably too costly to start with that due to the high cost of a compressor. For most automotive tools, I like OTC stuff (their compression gauge is P/N 5605). It's more expensive than Harbor Freight/Amazon Chinese Stuff, but less expensive than Snap-on, and the performance and durability are excellent.

 

[TRevs]

Me, too!


Agreed. In fact, I used my leak down gauges (OTC 5609) more often than the compression gauge. I find it to be a much more useful diagnostic tool.


Agreed, once again.


The problem with the older kits, like the Craftsman we both own, is that there have been several new spark plugs come into use (mostly smaller, since engines are smaller nowadays) since those kits were purchased. Most of the compression testers currently on the market have adapters for today's common spark plugs.


I, too, drive high mileage cars. My daily driver is a 26-year-old Subaru with 395k on it!


If I had to do it over again, I'd buy the leak down gauges first. However, you need to have a compressed air supply to use it. If you don't have that, it's probably too costly to start with that due to the high cost of a compressor. For most automotive tools, I like OTC stuff (their compression gauge is P/N 5605). It's more expensive than Harbor Freight/Amazon Chinese Stuff, but less expensive than Snap-on, and the performance and durability are excellent.

Im totally new to this; does a leak down test provide the same info as a compression test and mire, or are they totally different diagnostic tests?

I have a small kobalt compressor that goes to 125psi; would that suffice?

Have you had to replace rings or valves on your Subaru? A local independent Honda shop told me you can’t really do rings on these engines because machine shops aren’t doing that kind of work anymore, at least where I live (San Antonio). I really like my ‘07 Civic and would be willing to have the engine rebuilt if that could feasibly restore its original performance.

 

[sab]

Im totally new to this; does a leak down test provide the same info as a compression test and mire, or are they totally different diagnostic tests?

They both will help you figure out if a cylinder isn't sealing, but the leak down gauges will help you figure out the source of the leak. Basically, for each cylinder, you bring it to TDC on the compression stroke (valves closed), hold it there (breaker bar and socket on the crank nut), and then pressurize it. The gauges will tell you how much pressure is leaking. You can then listen for where the air is escaping (intake port, exhaust port, crankcase) to find the source.

I have a small kobalt compressor that goes to 125psi; would that suffice?

Yes

Have you had to replace rings or valves on your Subaru?

Yes. I completely rebuilt the engine 30,000 miles ago. The only thing I didn't replace was the pistons, only because there are no OEM or aftermarket pistons available anymore.

A local independent Honda shop told me you can’t really do rings on these engines because machine shops aren’t doing that kind of work anymore, at least where I live (San Antonio). I really like my ‘07 Civic and would be willing to have the engine rebuilt if that could feasibly restore its original performance.

That sounds like someone didn't want the work. Unless there's something odd about that Honda engine, I don't know why someone wouldn't be able to do rings. I will tell you that quality in the automotive service world is absolutely horrible these days, and shop rates are high. That's why I do my own work. A few years back, I got screwed on a rebuilt engine I had to pay someone to do because I was out of state. That engine, and two warranty replacements after that one, didn't even last 10,000 miles! I ended up buying a genuine Ford OEM long block and re-doing it myself...

 

[ColoJeep]

A few years back, I got screwed on a rebuilt engine I had to pay someone to do because I was out of state. That engine, and two warranty replacements after that one, didn't even last 10,000 miles! I ended up buying a genuine Ford OEM long block and re-doing it myself...

This sucks sab ! , and it shows that the demand for engine machine work has dried up and the great machinists have retired .
Most people won't change their own oil , let alone overhaul an engine. Since there's not a smartphone app. for that , our society must buy over priced , disposable cars ( Que @Zorba ) .

 

[TRevs]

They both will help you figure out if a cylinder isn't sealing, but the leak down gauges will help you figure out the source of the leak. Basically, for each cylinder, you bring it to TDC on the compression stroke (valves closed), hold it there (breaker bar and socket on the crank nut), and then pressurize it. The gauges will tell you how much pressure is leaking. You can then listen for where the air is escaping (intake port, exhaust port, crankcase) to find the source.


Yes


Yes. I completely rebuilt the engine 30,000 miles ago. The only thing I didn't replace was the pistons, only because there are no OEM or aftermarket pistons available anymore.


That sounds like someone didn't want the work. Unless there's something odd about that Honda engine, I don't know why someone wouldn't be able to do rings. I will tell you that quality in the automotive service world is absolutely horrible these days, and shop rates are high. That's why I do my own work. A few years back, I got screwed on a rebuilt engine I had to pay someone to do because I was out of state. That engine, and two warranty replacements after that one, didn't even last 10,000 miles! I ended up buying a genuine Ford OEM long block and re-doing it myself...

This shop is where the NSX owners go, so I thought he would be knowledgeable. I figure I could learn enough to do it myself although it would probably take me months.

Does one have to acquire a lot of expensive tools (engine hoist/stand etc)? Are there steps that have to be done by a shop like resurfacing the head/block? Sorry for my ignorance.

 

[Zorba]

This sucks sab ! , and it shows that the demand for engine machine work has dried up and the great machinists have retired .
Most people won't change their own oil , let alone overhaul an engine. Since there's not a smartphone app. for that , our society must buy over priced , disposable cars ( Que @Zorba ) .

 

[sab]

This shop is where the NSX owners go, so I thought he would be knowledgeable.

If he's used to NSX work, he may not want to do "lowly Civic" work.

Does one have to acquire a lot of expensive tools (engine hoist/stand etc)?

Yes, to rebuild engines you do need a fair amount of special tools. I've been building my tool collection for almost 50 years, so it's pretty complete (although, is it ever really "complete"?)

Are there steps that have to be done by a shop like resurfacing the head/block?

Yes. To properly rebuild a head, you have to send it to a machine shop (unless you have a machine shop). The block doesn't usually require machine shop work unless the cylinders are scored. I usually hone with ball hones in a hand-held drill.