GUNSONG4101 Hi-Gauge Compression Tester

This compression tester by Gunson, is an extremely useful tool which can assist the diagnosis of an engine which isn't working as it should. Computer diagnostic tests don't seem to pinpoint some faults as the 'Check Engine Light' (CEL) doesn't always turn on, or generate a fault code.In my case, the engine has lost power, is very thirsty on fuel and has a irregular idle - but no CEL or fault codes. Using this compression tester has revealed one of the cylinders has a much lower pressure test reading than the others (two of which are also lower than they should be). The cylinder head will need to be removed to investigate this problem as I'm pretty confident now the valves are not sealing correctly or may be damaged.Before you commence the compression test on your engine, the following suggestions may be helpful:- Locate and remove the fuel pump fuse then start the engine and run it until it stalls - this is to ensure no fuel is injected during the tests.- Remove the spark plug leads and use cable ties to identify each lead (one cable tie on plug one, two on plug two etc) unless they are already marked.- BEFORE removing the spark plugs it is essential to clean around each spark plug to prevent dirt or any objects from dropping into a cylinder. Use a cardboard tube taped to a vacuum cleaner hose and push this over each plug and down to the cylinder head.- Ensure any small objects, which could pass through an open spark plug hole, such as screws or washers etc. are moved well away. It would be very difficult to retrieve these items from a cylinder without removing the cylinder head. If an item accidentally dropped into a cylinder un-noticed and the engine was cranked over or run, then serious damage to valves, the piston/rings, and cylinder walls would probably occur.- Disconnect the low tension side of the ignition coil to prevent it operating when the engine is cranked over. Failure to do this could result in damage to the coil pack (insulation failure) and/or the ECU, due to the spark plug leads being open-circuit !- Screw in the compression tester and open the throttle wide before turning the engine over.- Record each cylinder pressure.- Perform the 'wet' test if required, but afterwards run the engine for 15 minutes to burn off the added oil and so help to reduce damage to the catalytic converter.If you are intending to use this compression tester on a Ford Zetec engine (with black top plastic valve cover) or any other engine which uses 14mm spark plugs with taper seats - e.g. NGK type PTR5A-10 etc. then be aware the 14mm connector supplied with this kit will not fit ! The length of the threaded part isn't long enough to reach into the cylinder head and screw in - it will reach the spark plug hole by turning the rubber tube, but the threaded section in the cylinder head is recessed further into the head preventing the threads from engaging. In my case I have a modified adaptor which overcame this problem. I believe Gunson do manufacture an extension adapter for use with Zetec engines.To sum up, this is a very good quality and accurate compression tester - highly recommended.

Proved that my engine hasn't got a blown headgasket as I initially suspected. Works well and nice big clear readout.

Good product this - seems sturdy and well made with the two main standard spark plug fitments. Gave a fairly accurate reading against my garages more expensive kit so as a useful item in the workshop at this price its good value.

Superb product which, unfortunately, proved what I suspected (Very Low compression on cylinder 2 and a scrapped car)Very easy to use and clear display

I bought this tool to perform a compression test on a vintage car. The tool is well made, easy to use and well worth the investment.

I'm no mechanic but I wanted something sturdy and reliable to test the compression on my car to ensure my mechanic was not telling me porkies. I can't vouch for the accuracy as I don't have anything to compare to but it works fine and the results matched what my mechanic was telling me. The gripe I have with this is that the hose is too short and also the gauge rotates with the hose when screwing it into the spark plug hole. At times it doesn't quite turn enough to face you so you either have to slacken it a bit (which I assume affects the compression results) or you have to twist the gauge a bit to see it, which might damage its joint to the pipe if done too often. I think this is built sturdy enough not to break easily but would rather not have had to worry about it.Anyway, no complaints other than that. I've only used it to check all four cylinders in my car and not used since.

Easy to use on my old cb750. Looks robust enough for occasional and for the price is perfect.

Just checked compression on a car for the first time. Good quality, really easy to use, delighted with the product

Très facile d'utilisation, le clapet anti retour est situé dans le filetage qui va dans le puit de bougie de manière à avoir la mesure de pression la plus précise possible. Le flexible plastique est de très bonne qualité et ne vrille pas lorsque on veux visser le filetage.

Buon manometro, niente a che vedere con il materiale cinese in vendita a poche decine di euro. Valvola di tenuta sulla parte filettata da avvitare alla testata e NON sul manometro, quindi lettura il più vicino al reale del RDC del cilindro. Fornito in confezione tutto sommato economica (da espositore) ma materiale dello strumento comunque ottimo.....ed è quello che conta. Misure accurate, ripetibili e confrontabili quindi ottimo se state facendo modifiche e volete apprezzarne gli effetti.

Wie man sieht Funktioniert perfekt im Gegensatz zur halb so teuren China Variante, ausserdem ermöglicht der lange Einschraubstutzen eine einfache Montage.

Primero compré uno de esos de la caja azul. Ya dejé el comentario: Una estafa: se demonta, el mismo proceso de medicion con 5 segundos de intervalo arrojaba resultados diferentes... Muy mal... Luego le pedi uno a un mecanico amigo... Segun ese, la compresión de mi moto estaba al límite inferior, ya no tenia mas compresión.... Una moto con 40000 kmts ya no tiene compresión en ninguno de los 4 cilindros???Compré el Gunson. La moto esta al 95% de la compresión indicada. Medí otra tertacilindrica que tiene 265000 y la compresión esta al 10%. Monocilindricas he medido 3 y la relación kmts, estado y compresión medida, me deja tranquilo...

fait bien son boulot très sympa et surtout un bon prixMais il manque une mallette pour le rangement.