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EH 161 Red Motor - low compression cly. 5
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Hi
I have an EH with a 161 motor. Runs well, but noticed missing a bit, with audible "puffing" sound from exhuast at a ration of about 1 for every 2 motor revolutions. Ran compression test, all cylinders between 155 & 170 psi with the exception of No. 5, which is at 65 psi!
The plugs all look clean (no oil). Motor does not leak an abnormal amount of oil (i.e., don't think it's rings). Adjacent cylinders No. 4 & No. 6 are both 165 psi (i.e., does not appear to be head gasket). My verdict is the No. 5 exhaust valve.
Prior to ripping head off (it's my get-to-work car), is my thinking sound?
Matt
Holden man working on a Ford. |
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You can try a cylinder leakage test to give a good determination of fault. This is done by placing the ylinder to be tested to TDC, top dead centre. This will have the valves closed. You can mae your own tool if you wish by removing the porcelain from the centre of a spark plug and braising an air fitting that matches you system to the steel outer of the old plug. You will then be able to inject air into the cylinder, 60psi will be sufficient. If the air escapes from the exhaust, exhaust valve fault, air from carby inlet valve fault, air in radiator gasket/head fault etc.
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If a compression tester is all that you have as opposed to a leak down tester squirt some oil into the low cylinder one or two squirts will do.
Do another compression test if the cylinder comes good it's likely the rings if there is little change it's a valve.
Could be something as simple as a valve not closing due to your lifters need adjusting or a more sinister thing like a burnt valve.
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Rank: Member
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Joined: 23/05/2009(UTC)
Posts: 107
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Thanks, will check those out.
Matt
Holden man working on a Ford. |
Continually amazing how people are willing to share information. |
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Rank: Member
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Joined: 23/05/2009(UTC)
Posts: 107
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Did the oil test - put 3 squirts down the plug hole, made little if any difference. Put 2 more squires to be sure, still on went up a couple of PSI at the most. Pointing towards valve. Also backed off both inlet and exhaust vavle adjusters and repeated the test - no change.
Guess head off is the next step. |
Continually amazing how people are willing to share information. |
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EH 161 Red Motor - low compression cly. 5
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