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Need a good shop - Knocking, clicking, low compression test, 1948 V12


jmotes

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I have a 1948 Continental with a V12.  Just bought it and last weekend took it out for it's first club cruise.  40 Miles to a nearby town.  I felt confident since the car had a ground up restoration including engine and transmission rebuild 14 years ago and less than 2000 miles on the car since.  Well my gauges didn't work, oil always showed 50 pounds, fuel always empty, temp, always maxed out and amps at zero movement, so when the oil gauge dropped to zero and then bounced around, I thought nothing of it... until the drive home.  Engine clicking, turned into a heavy thumping knock.  I made it home and the engine does run, but it's not sounding good.  I did a compression test and My readings are as follows

105

90

95

91

100

98

105

97

90

91

95

105

 

The manual says pressure should be between 105 and 125... so I'm not looking great.  I do think my car was warm, but i only ran it for 10 minutes before running the test.  I added oil to three cylinders to do a wet test and the scores came up to 100, 101, and 100 for previous scores in the 90s.  So it looks like overall my compression is low, I suspect the sounds aren't from just a cylinder but are valve and perhaps lifters, etc.  I'm considering having the engine rebuilt, looking for a shop that really knows these engines and will not cut corners.  I want it running better than new.  Any thoughts out there?

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I think you'd better get the gauge wiring up to snuff before visiting the rebuild shop.  If the car is running, the ammeter should work.  Gas sending units are known to stick.  You can test temp. gauge by grounding and opening.  Do you have enough oil in the crankcase?  Then maybe you'll be lucky and solve the running problems with good oil, and maybe a can of STP or similar.

Abe

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To read your first post, I would not be that concerned with the compression readings (all in or around 10% of each other)

 

I am concerned about sudden loss of oil pressure and knocking from the engine

 

Hard to say without actually hearing it, but my suspicions would be more towards the bottom end

 

Spun bearings will have virtually no impact on compression readings

 

A stuck valve or a bent push rod or a wiped cam lobe will effect compression readings as well as ring or piston damage

 

A wet test (with oil) really is only to see how bad the rings are, if it makes a considerable difference, the rings are shot

 

I hope this helps, but its not good news

 

Avoid running the engine if you can until its sorted, the less its run, the less its damaged

 

Mick

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  • 3 months later...

Thank you for your input.  I've been prepping the engine to pull it out and found some issues that made me think I'll just rebuild and then I'll be comfortable driving the car.  Whoever rebuilt this engine (it is supposed to have been done over a decade ago, but only driven 1000 miles since) did some strange things... or the owner did.  Maintenance seems to be an issue.  I removed the exhaust manifold without breaking a sweat.  There was no torque on any of those bolts.  I could have taken a couple off with my fingers only.  Finding this in other areas.  it's like it was thrown together in a hurry.  I'm having H&H rebuild it as soon as I get it out of the car.  Tonight should do it.  Now the next question.  Where can I get my hands on a wiper motor and does anyone have good documentation on the vacuum and hydraulic systems?

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