B30 shenanigans.

[guitarman]

I recently changed the distributor cap, rotor arm and points on my 164 and set the timing and dwell angle. Unlike on previous occasions it just wouldn't idle smoothly.
Before it was 50p balanced on the rocker cover smooth, this time it was a bit rough and there was a slight 'put put' sound coming from around No.1 cylinder's top end.
Took her to a show on Sunday and she was a bit hesitant at low revs; fine once revs were up though. Anyhow, after returning from the show I noticed she was running hot; not enough to boil but definitely hotter than usual. I flipped the bonnet up expecting to see a slipping fan belt but then realised the engine sounded very agricultural- at least when idling. I lifted the oil cap- normal, looked into the expansion tank and there were no oil slicks so I felt better.
Then noticed that the engine smoothed out when revved.
I'm thinking that there is either a vacuum leak to atmosphere around the intake manifold gasket near cylinder No.1 or a leak between intake and exhaust ports of cylinder 1&2?
The hot running would suggest to lean a mixture although the engine sound makes me think it's exhaust gas venting into the intake. Looks like a manifold gasket will be on order.
Anyone had to replace theirs? Similar symptoms?

[Triple-S]

Coincidence - yesterday I took my 164E to a show as well, and on the way back the temperature gauge went up a lot. Not too hot so continued home OK.
This morning in the heavy rain had a quick look under bonnet - oil OK but there seems to be an air lock in the top hose, and the water pump fan shaft is wobbly - another pump methinks. Whilst parked the fanbelt tension was OK but obviously it fluctuated with the pump shaft shot now: no other problems though, engine still quiet and running fine.
If dry when there Wednesday will attend to water levels and try it again: its been a long time since I did a manifold gasket, but failure isn't unknown. I expect you'd hear it if the manifold has cracked - again not unknown.

Paul

[guitarman]

I can't hear any hissing sounds around the manifold; I think I'll get a can of brake cleaner and give it a few squirts around the gasket to see if that shows any change in the engine sound. I do think it's internal though, it does sound very noisy and 'flatulent' when idling.
It's about time the engine bay got some attention so I may get the carburettors overhauled and the brake vacuum reservoir painted.
Maybe even get the outside of the manifold painted- high temperature paint?
The car is overall a good one but it's getting to the stage where I'd like to either sell it or turn it into a very good one!

[guitarman]

Did a compression test this evening; all cylinders were 125-140 psi cold which is good so I'm 99% sure it's not the head gasket.
Then I checked the timing; way too retarded. So reset to 10°. This meant that idle was up to around 1200rpm, presumably because of the vacuum leak. The difference in performance was very marked though, goes like a demented tram now, no hesitation at all.
I also stuck a length of fuel pipe in my ear and I'm sure there's a put put sound underneath the intake part of the manifold at cylinder No.1; so a new manifold gasket is on order and replacement will commence soon.

[Derek UK]

Leaks at the exhaust manifold to down pipe are pretty common and can make some pretty odd sounds. Worth checking. Don't burn yourself.

[guitarman]

Originally Posted by Derek UK

Leaks at the exhaust manifold to down pipe are pretty common and can make some pretty odd sounds. Worth checking. Don't burn yourself.

Yes! I did replace the exhaust a couple of years ago; would a leak there produce the symptoms I described? One thing I haven't done is checked the brake vacuum hose. Pretty sure it's the manifold, underside of intake for cylinder No.1 where you can't see. The manifold nuts weren't exactly tight but tightening hasn't helped!