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Re: mga II frothy engine, and other questions

To: "Clayton Kirkwood" <kirkwood@garlic.com>, "mgs" <mgs@Autox.Team.Net>
Subject: Re: mga II frothy engine, and other questions
From: Barney Gaylord <barneymg@ntsource.com>
Date: Mon, 06 Jul 1998 23:34:09
At 02:46 PM 7/6/98 -0700, Clayton Kirkwood wrote:
>In trying to fix up various problems on my mga, .... In taking the valve
cover off, I noticed a significant amount of white froth, I presume oil and
water.

Right on.

>Other significant facts:
>
>Oily sludge in the cooling system.

Bad seal near the left rear corner of the head gasket where there is a
pressurized oil feed hole from the block to the head to lube the rocker
shaft via the rear rocker pedestal.  You could try to re-torque the head
bolts and change the oil, see if that helps.  But, when one starts to leak
in that location, you normally need to replace the head gasket to fix it.

>Going through oil fairly quick.

Yep.  Pressurized oil leak.

>Definite bad valve cover gasket (replacing). Maybe other oil leaks.

Different problems, but still bear fixing.

>In running a compression test, I have 130, 60, 130, 85 back to front.
After squirting oil into each cylinder, I had 135, 70, 130, 90, again back
to front. Assume rings ok.

Rings don't look too bad there.

>Given the low readings for two non-adjacent cylinders, along with froth,
and an oily sludge in the cooling system, I assume that I have either two
cracks in the head,

Not necessarilly.  Head cracks are usually around the center exhaust valves
(#2 & #3) and usually do not involve oil leakage.

>a gasket break in two spots,

Maybe, but not very likely.  If there was that much compression loss past
the head gasket, you should notice one of two conditions.  One would be
some visible leakage around the head gasket at the side of the head while
the engine is running.  The other would be a tendency for the car to blow
the coolant out of the radiator past the pressure cap from cpmpression
leakage into the water jacket, especially with hard driving.

>and/or bad valve guides 

Would see oil consumption and smoking out the tail pipe, especially on
startup.

>and/or bad valve seats and burnt valves.

Good bet.  Probably a couple of burned exhaust valves, or may carboned up
intake valves.

Time for a simple blow down test.  Rig up an air line to a spark plug
threaded fitting.  For this you might break the ceramic off an old spark
plug and weld on a quick connect air fitting.  Otherwise you may be able to
buy such an adapter at a parts store.  Screw the fitting into a spark plug
port, rotate the engine to top dead center on the compression stroke for
that cylinder, and apply low pressure air, about 15-20 psi will do nicely.
Then listen around for hissing noises.  Hissing at the carburetors
indicates a leaky intake valve.  Hissing at the tail pipe indicates a leaky
exhaust valve.  Hissing at the oil filler hole indicates leakage past the
piston rings.  Repeat this test for each cylinder.

You also want to do a pressure test on the cooling system.  If you don't
have the $90 tool kit for this, any radiator shop will do it for you in a
few minutes.  Fill the coolong system to the top with water, as little air
space as possible.  Install the pressure tester to the radiator filler
neck, apply about 10 psi presssure, and wait a little while.  If the system
is pressure tight is will hold the pressure for several minutes.  If the
pressure drops more than 2 psi in the first minute, you have a coolant leak
somewhere.  Start by checking the radiator and the heater and all the hose
connections for leaks, as well as the thermostat housing, the water pump
front seal, and all around the cylinder head.  If it's losing water, and
it's not coming out on the outside, then it's going into the oil sump.
Most likely cause then is a leaky head gasket.

>.... How difficult is it to remove and check the head?

First time around, several hours to R&R the head.  Second time around, 3-4
hours under a shade tree.  Do the diagnostic stuff first to determine if
it's really a head problem.  You may save yourself some work if it's not.
You can easily remove the head yourself.

If you're not really up on cylinder head maintainance, you should take the
head to an engine shop where they can disassemble and clean and inspect it
properly.  If you suspect a crack, ask them to magnaflux it.  Up to that
point you may owe the shop $30 or so, and you will have everything you need
to know to make an informed decision on what happens next.  They will be
happy to tell you what it costs for a basic valve job, some new valves if
needed, new guides, and maybe hardened steel valve seat inserts.

>.... I am more interested in getting it going correctly - am I better off
getting an expert to rebuild at this point? If so, I figure now is the time
to do a complete rebuild and upgrade like crossflow head, upgraded valves,
seats, guides, cam, and rocker. ....

Get an opinion and advice from a machine shop after a close inspection of
the head.  A standard valve job is not very expensive compared to a lot of
the other things you mention here.

Test first before disassembly.  Inspect closely before spending $$$$.

Barney Gaylord
1958 MGA with an attitude


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