gas 44 Posted January 22, 2011 Share Posted January 22, 2011 Hi can anybody tell me what the psi should be on a willys engine per cylinder we have about 80 psi and wanted to know how that compares. Thanks in advance,Gary Quote Link to comment Share on other sites More sharing options...
Blackpowder44 Posted January 22, 2011 Share Posted January 22, 2011 In answer to your question I have just been looking through my EMERS regs for Jeeps and it states, Min. compression at starter speed with engine warm 105lb./sq.in. John. Quote Link to comment Share on other sites More sharing options...
Essex5 Posted January 22, 2011 Share Posted January 22, 2011 Without knowing that particular engine, I assume it's fairly low compression by design, so 80psi sounds reasonable for an old'un. The main thing to look for on any old engine is that all the pots are fairly similar. I speak as someone who has been tinkering with old LandRovers for forty-plus years.:nut: John Quote Link to comment Share on other sites More sharing options...
gas 44 Posted January 22, 2011 Author Share Posted January 22, 2011 Thankyou thus far. As to the age i understand it to be between "42 and 44" oh and i maybe should have said its petrol :laugh:. Quote Link to comment Share on other sites More sharing options...
Jessie The Jeep Posted January 22, 2011 Share Posted January 22, 2011 Mine had a test a couple of years ago, and from memory they were around the 110psi range. The engine is from August '44, but had been rebuilt by the French in 1987, but I don't think it had much use after that until I got it. At the point of testing, I'd done around 8,000 miles. Quote Link to comment Share on other sites More sharing options...
deadline Posted January 22, 2011 Share Posted January 22, 2011 IIRC the range is like 105-115 with less than 10PSI diff from highest to lowest reading. You really need to have a LEAK DOWN test down. A compression test will tall you the compression of the cylinder, but if its low it will not tell you WHAT to fix: Rings? Valves? Cylinder? Most mechanics will simply guess at a low PSI cylinder. Why sleeve a cylinder when the valves are the problem? Any good shop should have a leakdown tester, or you can buy one (in the US they are about $30) Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 22, 2011 Share Posted January 22, 2011 You really need to have a LEAK DOWN test down. A compression test will tall you the compression of the cylinder, but if its low it will not tell you WHAT to fix: Rings? Valves? Cylinder? Most mechanics will simply guess at a low PSI cylinder. Why sleeve a cylinder when the valves are the problem? You can usually tell if it is rings / bore by doing a second test with a drop of oil down the bore, anyway once you have determined it is low, then it has to have the head off for examination. Bore can be measured for wear, if not visually obvious. Another point to note is if two adjacent cylinders are low with virtually the same readings, this could indicate a head gasket blow, common on a lot of side valves where gaskets are narrow around the valve area. Quote Link to comment Share on other sites More sharing options...
gas 44 Posted January 23, 2011 Author Share Posted January 23, 2011 Thankyou all again,should the psi be measured when engine is hot or cold ? Quote Link to comment Share on other sites More sharing options...
alant Posted January 23, 2011 Share Posted January 23, 2011 You should measure compressions with the engine warm. I have a leak down tester and am near Tring Herts. Quote Link to comment Share on other sites More sharing options...
deadline Posted January 23, 2011 Share Posted January 23, 2011 (edited) You can usually tell if it is rings / bore by doing a second test with a drop of oil down the bore, anyway once you have determined it is low, then it has to have the head off for examination. Bore can be measured for wear, if not visually obvious. Another point to note is if two adjacent cylinders are low with virtually the same readings, this could indicate a head gasket blow, common on a lot of side valves where gaskets are narrow around the valve area. There are some haphazard ways to try and determine the health of a cylinder. The best and easiest way, hands down, is with a leak down tester. Its an all in one test that can rule out valves, cylinder and rings in one shot.. and you can take all day to do it (as long as you have air). You can use a compression gauge and various potions and incantations.. that might get you close. But the ease of which a leak down test will get you the same info is so much easier and faster. I would never allow (or perform) an engine disassembly on a hunch. The costs and wasted time looking at the wrong components is just that.. a waste. On a compression thest the following things can affect the readings: valve timing, starters ability to crank engine, battery amperage/voltage. A leakdown test can be done on the entire length of the power of compression stroke (as long as the valves are closed). Proper tool for the job. In 2011 that tool is a leak down tester. I have not looked extensively, but I do not believe that the Tms for the GPW or MB even list a compression psi. Only that they are 6.5:1 compression ratio engines. Edited January 23, 2011 by deadline Quote Link to comment Share on other sites More sharing options...
Blackpowder44 Posted January 24, 2011 Share Posted January 24, 2011 The info I previously gave is from a set of jeep emers and is correct. Clive took a copy of my files and if in doubt you can check mup with him. I tried to put the page on here as an attachment but was refused as it was too large. John. Quote Link to comment Share on other sites More sharing options...
deadline Posted January 26, 2011 Share Posted January 26, 2011 Whats an EMRS? None of the US Army TMs (TM9-1803A/B, TM9-803) list a PSI. Even TM10-1513 is mute on compression readings. Is that a civilian manual? I have hears the 105-115psi spec also, but never in writing. Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 26, 2011 Share Posted January 26, 2011 Whats an EMRS? It is EMER to be precise. Electrical and Mechanical Engineering Regulations. These are British Army technical publications to cover all aspects of engineering within. Even if the equipment is made outside of the UK, there will be data of some sort covered in EMER's. They started off in WW2. Quote Link to comment Share on other sites More sharing options...
gas 44 Posted February 27, 2011 Author Share Posted February 27, 2011 Hi everyone,thankyou all for your input and special thanks to "alant" for his very kind offer. Just an update really,after getting the engine to start (and thats a story in its self) we found that we did indeed have a psi of 105 when warm which is about on the button as to what people posted here. Thanks again Gary Quote Link to comment Share on other sites More sharing options...
Jessie The Jeep Posted June 11, 2011 Share Posted June 11, 2011 I just re-set the tappets on my Jeep today. Prior to adjusting I was getting 86-105-105-105psi. The tappet gaps had closed up or were non-existant, so were re-set to 0.014 thou. After re-setting, the cylinder pressures were checked again and were all around the 115-120psi range. Quote Link to comment Share on other sites More sharing options...
gas 44 Posted June 14, 2011 Author Share Posted June 14, 2011 Hi Steve,thanks for the info and update. Maybe you could come over to do ours . After getting the jeep engine running we have fully stripped the whole jeep to nuts and bolts.We were horrified at the state of the chassis,still now work in progress. We are still a long way off....so far that we have brought a dodge(wc 51) to play with in the mean time. Had a good run to Wickstead at the weekend and pleased with the drive of the dodge after nearly getting to grips with the down shifting. Thanks again. PS I wished my models looked like yours. Gary Quote Link to comment Share on other sites More sharing options...
Jessie The Jeep Posted June 14, 2011 Share Posted June 14, 2011 Drive it up, I'll do it over lunch, then you can drive home in the afternoon!! Quote Link to comment Share on other sites More sharing options...
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