TD5 compression test readings

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Originally Posted by 400HPONGAS

Well Bundalene , your mechanics are right , except id say over 450 would be better .There are just so many parameters/conditions as to what the theoretical Presure actually is that its all rather irrelevant .Next time you Comp check it do it with the Glow plugs fired up and see what that does , then add a little engine oil , then disconnect the main air feed to the plenum/manifold so its not restricted, then do it on a 10 degree day and a 35 degree day , etc etc etc . the figure is 19.5:1 a static CR not the Dynamic CR ,the pressure is irrelavent , how does it perform ?

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From memory you build or used to build high performance petrol engines.

I reckon the pressures are all right but in a diesel you don't add oil when doing a compression test, unless you have low pressures and you want to isolate valves or rings.

Reasons are people have inadvertantly added to much and either the engine will fire on the oil added or the volume of oil will hydraulic the engine.

The big thing to look for is even pressures across the cylinders with no more than 10% difference ideally.

Thats what I was taught at trade school any way.

great thread.

I was thinking about doing a comp' test wouldthis do the job
Brand New - Diesel Compression Tester | eBay
CHeers

Matt

Hey Matt,

Yes and No.

There are only 4 glow plug ports in a td5 so you need to make an injector based tool to read the pressures....

so yes the gauge and hoses would be fine, but the connection options to the head wouldnt.

cheers
Pete

Thanks Pete.

Any sugestions out there for the correct injector whole fitting and how would I go putting it on this kit or is there another kit out there that would do the jod?

cheers

Matt

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Originally Posted by Psimpson7

Hey Matt,

Yes and No.

There are only 4 glow plug ports in a td5 so you need to make an injector based tool to read the pressures....

so yes the gauge and hoses would be fine, but the connection options to the head wouldnt.

cheers
Pete

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I borrowed a compression tester, but will be putting my own together sooner or later, based on something like that kit. These Ebay kits use a quick release air line type fitting with BSP adapters.

The kit I used had an adapter which looked like a hollow injector from a 300TDi, for which I made a bracket to hold this into the TD5 head (using new copper washers). Pity I didn't take any pics at the time.

I haven't come across any 'off the shelf' compression tester for the TD5, however, there could well be one.

Erich

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Originally Posted by Bundalene

I have been trying to find out the correct pressure readings for a TD5 compression test, say for a new engine and also what is acceptable.

I have done a compression test on a TD5 engine and the results were between 430 - 450 psi., done through the injector hole. I am unsure whether this is good or bad, I assume it is quite OK.

The test was done dry, I have since been told that tests should be carried out with a squirt of oil in the top of the cylinder

Also with a compression ratio of 19.5 : 1 there is a formula or method to convert this to psi.

Erich

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Quote:

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Originally Posted by Bundalene

I have been told by 2 mechanics that over 400psi for a diesel is good. Does anyone have figures for a TD5

Erich

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Erich
Land Rover never quoted actual compression figures for the Td5,so you would be looking till your blue in the face to find factory figures.

The figures quoted by the mechanics will be fairly close to being correct.Land Rover list the compressions on their other diesels as being approx. 24Bar and in the U.K it is generally accepted that anywhere from 24 -30 Bar is considered to be correct for the TD5 taking into account thermal dynamics as well,as long as all the cylinders fall into the maximum 10% variance factor mentioned earlier,personally I would like to see no more than 5% variance.

Wayne

Any tips out there for making an adapter out of the TDi injector?

Thanks

Matt