Since it needs rebuild, might as well give it some balls.
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| compression test #s https://slantsix.org/forum/viewtopic.php?t=33432 |
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| Author: | zorg [ Wed Jan 21, 2009 9:01 pm ] |
| Post subject: | compression test #s |
I've been noticing a loss of power lately. I'm having to down shift on slight grades I used to hold a gear on. - '76 Dart Swinger 225/833OD - 230,000 original miles - Next I noticed I was way low on coolant. Filled it up, and couldn't find any leaks. Haven't lost any since. Changed the oil, and took a trip up the interstate and back (600 miles). Upon my return I was foaming at the mouth, er, oil cap... Just your typical milkshake looking stuff associated with a head gasket leak. Just did a compression check. Here are my numbers, second set after squirting in some oil (front to back): 112 - 118 - 112 - 105 - 115 - 100 115 - 120 - 118 - 120 - 119 - 120 Spark plugs are nasty black. Maybe 7,000 miles on them max (full tune up). Uses around 1 quart per 1,000 miles. I was thinking head gasket, but with no new coolant loss, and the compression numbers being even across the board, I'm not so sure anymore. Any input, ideas? |
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| Author: | Doctor Dodge [ Wed Jan 21, 2009 9:05 pm ] |
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Have you tried retorquing the head? DD |
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| Author: | zorg [ Wed Jan 21, 2009 9:53 pm ] |
| Post subject: | |
Nope, I'll do that in the morning. Captain obvious here: then do another compression check to see where we are at? This is helping already, I would have never thought to try that. |
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| Author: | Joshie225 [ Wed Jan 21, 2009 10:14 pm ] |
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If the engine is running cold you'll get that foamy gunk in the valve cover. Burning gasoline produces water vapor and the engine temperature must be high enough to evaporate the moisture that passes by the rings to keep the oil free of condensation. |
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| Author: | SlantSixDan [ Wed Jan 21, 2009 10:26 pm ] |
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Number-3 rings are looking suspect to me, with that 15-pound jump on dry vs. wet compression reading. One quart per 1000 miles is also rather high oil consumption. Bet if you pull the PCV valve out of the valve cover and remove the breather duct hose from the (rear) breather cap, then start the engine and put one hand firmly over the PCV hole and the other firmly over the breather hose nipple, before long you'll have significant pressure wanting to escape past your hands. At 230k miles, if you freshen the head, the bottom end (rings, bearings) will not live very long at all; the increased sealing up top will finish off the bottom end. You are very probably nearing rebuild time. |
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| Author: | Reed [ Wed Jan 21, 2009 10:34 pm ] |
| Post subject: | |
I agree with Dan. The last 225 I pulled apart and measured had compression readings similar to yours and the cylinder bores were way past service specs. The motor ran great but lacked power and had bad gas mileage. I say save up and buy a new motor or get that one rebuilt. |
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| Author: | rosie [ Thu Jan 22, 2009 4:54 am ] |
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Since it needs rebuild, might as well give it some balls.
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| Author: | Wizard [ Thu Jan 22, 2009 6:53 am ] |
| Post subject: | |
On that worn out engine with low compression, does that fit the dry sooty plugs even the fuel is not excessive? Cheers, Wizard |
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| Author: | zorg [ Thu Jan 22, 2009 5:55 pm ] |
| Post subject: | |
Quote: Have you tried retorquing the head? DD
They were all at 70ft/lbs per the FSM specs. Quote: If the engine is running cold you'll get that foamy gunk in the valve cover.
I've been meaning to change out the 160 thermostat for a 195 to try to get some heat out of the heater anyway, so I finally did that today.Quote: The motor ran great but lacked power and had bad gas mileage.
Runs pretty good, and pulls a constant 20mpg.Quote: Since it needs rebuild, might as well give it some balls.
No worries there!SSDan, I didn't get a chance to try your pressure experiment today. Tinkered on the car a little today. Noticed the rear main seal leaks pretty good. The power steering pump can't keep fluid contained either. (Anybody on the I5 corridor have a manual box/column for cheep?) So the general consensus is that it's rebuild time? Looks like I have my research cut out for me. Thanks guys! |
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| Author: | SlantSixDan [ Thu Jan 22, 2009 7:05 pm ] |
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Quote: I've been meaning to change out the 160 thermostat for a 195 to try to get some heat out of the heater anyway, so I finally did that today.
Oog…yeah, a cold-running engine (such as one that has been mis-equipped with a 160° thermostat will tend to foul spark plugs and wear at a much greater rate than if it had a proper thermostat.Quote: So the general consensus is that it's rebuild time?
B'lieve so.
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