Midget 1275 comp.

[gregsdrums]

Ran a compression check on the cylinders today and didn't care for the results. 120 120 85 115. No choice now but to remove the head and see what I can find. Bent valve, pushrod, broken spring, ring, or bad head gasket? This may turn in to a complete overhaul... God I love these little british cars!

 

[Guest]

How about just a valve adjustment and see what you have then?

 

[gregsdrums]

Adjusted all, no difference. Also did "ping" test and blew air in cylinder. No change.

 

[twas_brillig]

Well, to quote Meatloat (adjusted): "three out of four ain't bad."
Seriously: borrow or rent a leak down tester and give it a shot. Not critical, but it might be able to tell you if it's rings or valves, which means pulling a head vs. an engine.
Touch wood, it'll be an exhaust valve - but I also believe in the tooth fairy.
Doug

 

[DrEntropy]

:lol:

Leak-down will tell more than a compression test does. Before you do any tear-down, perhaps giving it a water ingestion could clean up any detritus the valve seats may have collected... Worth a shot, IMO.


Spray bottle of water, rev the thing up to 2.5~3K and spray into carb pie-hole. Keep it revved and running! Oh, and do this well outdoors and downwind of anyone who'd be frightened by a LOT of white vapor clouds. :wink:

After that, a comp and leak test. :thumbsup:

 

[gregsdrums]

Well, the tooth fairy came last nite and removed the cyl head. To my eye (that of a self-professed sledge hammer mechanic)all looks good. Head gasket, springs, valves, but there was quite a carbon build up. Chipped some off a valve, looked like about 1/8" thick. Seats looked ok but I realize the tolerances are crucial. Tops of pistons and cylinders also look good. Hope the tooth fairy comes back tonite and does a leak down test...

 

[Guest]

O.K, while the head's off, put some rings and bearings in it. Lap the valves to make sure they're o.k and put it back together. You should have had the fairy do the test first. You already got it down, go ahead and put some new parts in it.


While I'm not a big fan of hone-in-car ring jobs, it was/is standard proceedure at evey Saturn dealership. Just make sure to rinse it well w/ hot soapy water.

If cylinder walls look really good and not worn bad, might want to consider doing the head instead of a lap job.

 

[recordsj]

what is the "ping test" procedure? what is the purpose?

 

[recordsj]

what is the purpose of spraying water into the carb and keeping the engine revd?

 

[DrEntropy]

what is the purpose of spraying water into the carb and keeping the engine revd?

It cleans a lot of the deposits off the piston tops and valves/seats by burning it off.

 

[recordsj]

how does the water clean the deposits off?
I see you say it burns it off, but how is it different than fuel going to the cylinder?

 

[DrEntropy]

Magic? Voodoo?



...my understanding is the water gets absorbed into the "coke" surface, then upon combustion the 2.5K°F flash front instantly boils the water, breaks up and burns off the detritus it has been soaked into as a result...

Internal steam cleaning of a sort.

All I know is: It WORKS. As long as you don't allow the engine to STALL in the process.

You can also reprofile SU or Zed-S carb needles with #600 wet-or-dry and an electric drill, set points gap with paper matches, adjust under-steer with an ignition key, stop a heater core from leaking with a pair of spark plugs... but I digress. :smirk:

 

[jessebogan]

Shhhh Doc, them is old timer secrets....

 

[DrEntropy]

Ooops. My bad.

...I guess uses fer th' Weasel Pee is okay to divulge tho?

 

[bugimike]

Shhhhh!!! ONLY for the initiated!!!

 

[bgbassplyr]

Youse guys quit giving away the 'secrets', please.

 

[smaceng]

If you ever have just one cylinder that is pulling in coolant, that will be the cylinder that is very clean. The water acts as a cleaning agent!
Scott in CA.