[Zmagnette] Engine Clatter & pressure drop

Paul Barrow paul.barrow at centurytel.net
Mon Nov 11 20:22:06 MST 2013

I know a very good crank rebuilder here in WA so if it is broke he may be
able to fix it, on the other hand it could be the relief valve, the pump . 


Solution, pull the engine and begin investigations.


There isn't much of a short cut as whatever you need to do, you wont be able
to do much with the engine in situ.



PS I don't have a TD . but I do have 3 Ys/YTs and have rebuilt a few XPAGs
in my time.


Paul Barrow

153 Clemons Road

Montesano, WA 98563 USA

+1 360 249 5123 Landline

+1 360 500 9389 Cell phone

+1 360 249 3776 Fax

Paul.Barrow at centurytel.net


From: zmagnette-bounces at autox.team.net
[mailto:zmagnette-bounces at autox.team.net] On Behalf Of jenntoo at shaw.ca
Sent: Monday, November 11, 2013 7:00 PM
To: List for the Z Magnette Group - North America
Subject: Re: [Zmagnette] Engine Clatter & pressure drop


Easy to tell if it is a broken crank.  Take off or loosen the fan belt and
see if you can easily move the crankshaft pulley a few degrees in either
direction.  If you can the crank is almost certainly broken.  The "T" series
cranks break whether the engine has been recently rebuilt or not and
breakage appears independant of the engine overall condition.  The thought
is that a harmonic vibration sets up in the crank at about 4100 rpm and
finally fatigues the crank and it breaks.  With the stump pulling 5.125 rear
ratio 4100 rpm is around 60mph.  Do yourself a favour and change the ratio
to 4.3:1.

    I broke one in the late 60's  Picked up a used crank for $25 from a
Worseley 4/44, had it ground, picked up a complete set of bearings, pulled
the motor, took off the pan and installed the 4/44 crank.  Nothing else was
done.  After I had the parts this was done in less than one day and I drove
the car for 10 years without any problem-mostly in the city of Sydney OZ.

             Hugh Pite

----- Original Message ----- 

From: Allen Bachelder <mailto:bachldrs at comcast.net>  

To: List <mailto:zmagnette at autox.team.net>  for the Z Magnette Group - North

Sent: Monday, November 11, 2013 6:12 PM

Subject: Re: [Zmagnette] Engine Clatter & pressure drop


OK, 5# oil pressure tells you it's hemorrhaging some place  If it's a
bearing, why should just one bearing catastrophically fail?  I rather like
the broken crankshaft theory.  A friend of mine had that happen recently
with his TF. As to repair, you can always get by for some time with a
minimalist approach if you don't drive it too hard or too much.  If all you
do is take it out on 40 mph club tours - about 500 miles per year, then that
might be OK. If you want it right, do what it takes to make it right.  You
may have to pull and disassemble quite a bit before you have your answer -
and by that time, it will not make economic sense to put it back together
with a minimal repair.  Most of us don't want to go this way more than


OTOH, a friend had to shut his TD down in Kansas on the Rallye to Reno due
to a horrible clatter that, after a tow back to Michigan, turned out to be
valve gear banging on an ill-centered valve cover! Of course that was not
associated with a loss of oil pressure...





Allen & Florrie Bachelder       =iii=<
Spring Creek Home for Wayward MGs

'57 ZB, '65 B, '69 C/GT, '73 B/GT

North Street, MI 48049, USA




On Nov 11, 2013, at 7:36 PM, Richard Greenberg wrote:

Still plenty of oil.  After I stopped, I restarted the engine to drive it
slowly a few hundred feet to a safe spot off the highway.  The engine has
never been rebuilt to my knowledge, but who knows its history? I have owned
it about 15 years. It has always run fine, although not super peppy.  

If it proves to be a bearing, does one just fix the offending bearing, or is
it a sign that everything is about to need redoing?

I haven't had time to look at the rockers or the bearings.


On Nov 11, 2013, at 5:25 PM, Steven Trovato wrote:



I think you have to investigate the problem before you can decide on a
course of action.  Sorry for stating the obvious, but there is still  plenty
of oil in there, right?  If something failed causing all the oil to pour out
on that hill, you would have a sudden drop in oil pressure and a whole lot
of clatter.  What is the state of this engine?  Recent rebuild or old and


-Steve T.


At 06:40 PM 11/11/2013, Richard Greenberg wrote:

Hi all,

    This is about my TD, but I bet you folks can help.

    I decided to drive the TD, instead of my Magnette, to our British car
club's annual BBQ.  About 25 miles out, running at about 50 mph uphill but
not too hot, the engine started clattering and the oil pressure suddenly
dropped to about 5 psi.  I had the poor car carried home.

    Any ideas about what happened? Rod bearing wiped out? Broken rocker arm?

    If it is one of those things, should I just make the repair, or is it
time to have the whole engine rejuvenated?





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