Compression Tester Kit

[RollingThunder]

Originally Posted by Derry

Thanks for the replies. I want to test to see if I have any issues with worn piston rings, leaking valves, head gasket etc. as I am getting smoke through dip stick after recently servicing the PCV system (twice). But it dose pass the glove test!

I found this Gunson 4101 tester for £20 in cpc.farnell which should fit with the 14mm thred on the hose.
https://cpc.farnell.com/gunson/4101/...ter/dp/CP01082

That looks identical to mine

[CNGBiFuel]

For this job, a gauge is a gauge is a gauge:

Originally Posted by DaveNP

..... I can't think of a scenario where I'd need to know the actual value to high level of precision. The ebay kit appears to have a lot of adaptors and extensions so should be useful for one off tests on other cars too.

Exactly that, what is the point to the question?

These things consist of a valve and a pressure gauge of varying quality. Nothing more. Unlikely, but let us suppose yours is wildly inaccurate? So what?

What you'd be looking for is one pot down on the others, at least one will remain decent. Take that as your high-point, and if the others don't come in at near the same, those would be where to look. If the gauge is accurate that's nice, but seeing as there's no simple way to check/calibrate, why worry?

Just look after the one gauge and use that same gauge, at 50,000 and at 250,000, and anytime you've bunged in a new set of rings - all knowing it can't be far out and if it is....? You're looking for relative pot-to-pot pressures anyway.

[richmac]

Hi Derry,

Looking through your PCV post, would I be right in saying that your PCV system was fine until you changed it? If so, I would re-visit that before looking for other problems.

BR,

Rich.

[CNGBiFuel]

Reading the PCV thread on this engine, can't see how it's possible to get a PCV that far wrong. A compression test is quick, cheap and easy to do. Needs doing anyway. If one or tow pots are down RMS etc is next. Best find out what is happening now.

At the price of these gauges, which would we want:

1) A cheap gauge with accuracy wildly out of spec which indicates an engine with all pots even.

2) A top quality gauge which shows not one of the OP's five cylinders is anywhere near the next. But calibrated to an inch of its life?

[Derry]

Originally Posted by CNGBiFuel

Reading the PCV thread on this engine, can't see how it's possible to get a PCV that far wrong. A compression test is quick, cheap and easy to do. Needs doing anyway. If one or tow pots are down RMS etc is next. Best find out what is happening now.

At the price of these gauges, which would we want:

1) A cheap gauge with accuracy wildly out of spec which indicates an engine with all pots even.

2) A top quality gauge which shows not one of the OP's five cylinders is anywhere near the next. But calibrated to an inch of its life?

Yes I agree I cant see what could have gone wrong, its a simple system, if anything its an improvement with the larger diameter hose. Just waiting to borrow one from an experienced DIYer, not sure which brand it is.

[CNGBiFuel]

Yes, let us suppose you HAD fouled it up which is doubtful, you'd have spotted it by now, and not repeated this.

Brand? I know you're from Derry, and that sort of thing is an obsession, I married a Newry girl thus I do know... but I swear this stuff all comes from the same factory, and a Chinese bloke somewhere sprays them red, orange, blue or black depending on the whims as to which Machine-Mart/Draper/Gunson/Clarke/Sealey/Harbor Freight/Halfrods/Jegs or SGS etc sticker we insist on? Am I just too cynical? It works though - for some of us - this thread is about swallowing it whole.

And anyone that does their own PCV including yours truly, isn't going to pay the £3-400 for a proper proper Sykes Pickavant / Snap-on/ Mac Tools etc gauge anyway? And there is no in-between, so why ask?

[Derry]

Did the compression test last night (Gunson). I got maximum 12 bar / 180 psi consistently on all 5 Cylinders. Haynes says it should be between 13 – 15. With teaspoon of oil they all went to max 14 bar / 200 psi.

Dry or wet it takes about 8 strokes for them to reach max bar.

I suppose the good thing is there was no difference between cylinders and at the moment car runs fine with no issues, not sure if there’s anything I need to do going by the readings. Any thoughts?

[volvo again]

As the engine gets older it will lose compression slightly due to wear of the pistons, rings, bores etc
The main thing it that all cylinders are showing a similar psi, this would indicate that the wear is consistant on all cylinders, a drop in compression on one or more cylinders would indicate a problem, as you know...
In your case I would be quite happy with the figures you got, if she's running well with no overheating etc all sounds good.

[CNGBiFuel]

I'm pretty sure you're fine. By 8 x revs you should see max. Those would be poor for an N/A car, you should see 220ish. We assume turbo, fact is, they're even, and don't improve much with oil, another good sign. My N/A car will see 250psi cold, with oil.

[Derry]

This one is a 10v 2.0 N/A engine CNGBiFuel.

Just quoting Haynes '...compression should build up quickly in a healthy engine, low compression on the first stroke followed by gradually increasing pressure on successive strokes indicates worn piston rings.' then it says if it improves with adding oil it indicates bore or piston wear.

Just out of interest is it a major job in fixing/replacing the bores or pistons, and would I need special tools for the job. How about the cost.