SL/R107 72 450SL: Rough idle, stall with puff of steam, large clear liquid leak

Jan 31, 2022 | 01:28 PM

R Esser

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Joined: Aug 2019

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'08 SL55 AMG, '72 450SL, '13 BMW ActiveHybrid3

72 450SL: Rough idle, stall with puff of steam, large clear liquid leak

Hi all, I just bought a '72 450SL w/ 72k miles, wondering if anyone's experienced these two things:

Stall with puff of steam at rear of engine when idling for ~20 mins
Pool of leaked clear liquid under the car, seemed to be coming from the rear of engine compartment but I couldn't pinpoint the source

For background, the car had been in storage in a garage for ~10 years. The previous owner's mechanic got it running (see below) but it idled rough. I let it idle for about 20 mins hoping it would even out as it warmed, but it stalled with a puff of steam at the rear of the engine. The leaked fluid didn't seem to be coolant, coolant level was okay after the leak, the fluid didn't have any noticeable oil, etc., contamination, it tasted sharp/maybe metallic taste.

I figured the timing probably just needed to be adjusted to fix the idle issue, but the ignition module seemed to die while I was tinkering. According to the mechanic who looked at it after me there was no spark so he replaced the FireBall.

Fresh work done:

Crane FireBall electronic ignition
Pointless distributor cap
Coil
Fuel pump
Fuel drained (car was in storage for ~10 years I think)

Any thoughts?

Jan 31, 2022 | 08:36 PM

chassis

Out Of Control!!

Joined: Sep 2018

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From: unbegrenzt

2017 GLE350 4MATIC

Please post pics of the SL!

Steam is water. Water comes from coolant. Coolant gets into the engine via the cylinder head gasket and goes out the tailpipe as steam.

Rough idle, steam and non-oil leak are textbook symptoms for failed cylinder head gasket.

Check all plugs and check compression. Suspect a failed cylinder head gasket.