e9 engine problems

studio128

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I've got a 73' e9 coupe that I got back on the road 6-7 yrs ago after watching it sit locally for years. apparently was rebuilt at 120k or so, and probably has 30-40k on it after rebuild. it's always run great, but the other day was driving my 90 yr old mom to the dentist and downshifted to second, slowly, and heard a metallic, sharp exhaust noise from underneath and looked back thinking maybe i ran over something and saw a puff of smoke...never smoked before. it now runs a bit rough cold and smokes on acceleration and downshifts. mechanic thinks maybe it "washed" a cylinder? have webers on it and the linkage on one seems loose. anyway, looking at a major rebuild it it's rings or scored piston...where to go on this? it's a beautiful, unmolested Baikal/black car...very little to no rust (lol) and a keeper for sure. so, 3.5 conversion, rebuild original, costs??? any advice or leads to a used
IMG_6255-1.jpg
motor appreciated
 

Luis A.

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If you believe it's a scored or otherwise damaged cylinder, get an Amazon $50 endoscope, pull the plugs and take a look.
 

JFENG

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a broken piston ring might explain the smoking. That's NOT necessarily a major repair. Pull the head/sump, remove offending piston and check for deep scoring. If none, re-ring, maybe re-bush/bearing, dingle-hone that cylinder, button her up and keep driving. Of course, once you go that far, it might make sense to do a full refresh.

But, based on what you heard, it sounds like something else external to the motor.

Do the quick check first for a broken ring: pull the plugs and inspect for excessive oil on one, and do a compression test.

John
 

sfdon

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I have 2 used motors available -

Free

Local pick up in sfbay area


Never ever take a head off a questionable engine before you do a leak down test.

Once the head is off you are in for a complete engine job even if it’s only a bad valve seat.
You have lost the ability to test the rings.
 

Wladek

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What colour smoke was? Blue or white?
Blue = oil = piston = piston rings = cylinder head valve seals
White / light grey = coolant leak = cylinder head
 

studio128

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....so Rick pulled the motor and no broken rings or scoring....there were 2 loose valves and those cylinders were correspondedly low, but no apparent reason for the sudden smoke and metallic sound I heard in the driveline before the happened. apparently the motor was rebuilt 20+ years ago, and used rings that were known to be problematic in a lot of 74-76 cars. only 40-50k on the rebuild, don't have the receipts but think it was German Motors in San Rafael, ca. sometime in the 80's? anyway, it's at the machine shop now, apparently we can reuse the pistons and waiting to see if we can get the valves seals/guides. excuse my ignorance in some descriptions here, I'm not a mechanic!
 
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