Pagoda SL Group

W113 Pagoda SL Group => W11x chassis cars => Topic started by: Hassan on June 25, 2025, 08:07:01

Title: W111 230s Low compression after engine rebuild.
Post by: Hassan on June 25, 2025, 08:07:01
Hello all.
I've just gotten my 230s motor rebuilt,
1) Sleeved the Bore size to Standard.(pistons were all good)
2) New Piston rings.(trw germany old stock)
3) new exhaust Valves and Guides, seals.
4) got the head checked for Cracks and Straightness..
5) checked the Block Deck
6) new gasket.

First time around after doing it up we found some problems with the valves and seals so we opened it up again and did the head job.

Put it back together ( reused the new head gasket)

Now I am getting a reading of 100-108 psi reading on all six cylinders.( Wet and dry) which I know is low for this engine and won't help me set up the car for idle.
( Checked all tappet clearances )
 
I'm at my wits end as to where the compression is leaking or why it's not building enough!

I maybe looking at it with blinders on so any help to bounce off ideas would be greatly useful.

Spare part support isn't all that good in India so I can't be throwing parts at the engine as that would mean a lot of wasting of time to import.

Thanks a ton in advance.


Title: Re: W111 230s Low compression after engine rebuild.
Post by: Mike Hughes on June 25, 2025, 13:38:23
Even though it is a new one, it's not a good practice to reuse a head gasket. I'm afraid you will need to get a new one.
Title: Re: W111 230s Low compression after engine rebuild.
Post by: Cees Klumper on June 25, 2025, 17:11:43
Maybe double/triple check the engine timing, perhaps the cam is out of sync with the crankshaft just enough to not create interference issue, but still allowing the valves to open such that compression is not built up properly. Just a wild guess.
Title: Re: W111 230s Low compression after engine rebuild.
Post by: Atazman on June 25, 2025, 17:26:02
Have you made sure your pressure gauge is accurate?
Title: Re: W111 230s Low compression after engine rebuild.
Post by: kampala on June 26, 2025, 01:01:15
Perform a leak-down test.   This should reveal if the leak is the gasket, intake valves, exhaust valves, or rings. 

Title: Re: W111 230s Low compression after engine rebuild.
Post by: Ozone on June 26, 2025, 13:44:30
A leak down will tell you a lot. Stating the obvious, but find the issue before throwing parts at it.
Were the head bolts replaced? Are the compression numbers at operating temp?   
Title: Re: W111 230s Low compression after engine rebuild.x
Post by: Hassan on July 02, 2025, 06:13:59
Ok so I’ve the engine to idle around 900rpm. Waiting on. Head gasket and a leak down tester  I’ve ordered online . Yes compression gauge is fine as I cross checked with another one I have.

Since I’ve been running it on the stand for the last week or so the compression has increased slightly by 5psi (now at 115 psi) across all cylinders and she has started to idle well ,vacuum gauge  needle stay steady at 13 inches of mercury (i know you need 14 min) .  Could it be that the new rings and valves are bedding in?

I had blocked the pipe  on the intake manifold in between the carburettors to tune the carbs they seem to be almost there my question Is  should I run the engine while it’s blocked or open ended.? Opening it increased the vacuum reading to 14-15 .

Regards

Title: Re: W111 230s Low compression after engine rebuild.
Post by: Hassan on July 05, 2025, 07:52:06
Update:
 Still waiting for the gasket and Leakdown tester. Did. A quick compression test again today. All the values have dropped down to 95( first 3 cylinder)-100 psi.
Engine runs but not very well now

Would this be indicative of a head gasket failing or something else?