THE HIGHLY RESPECTED NEAL CAINS POINTED OUT IN THE BRITISH OCTAGON CAR CLUB
MAGAZINE SEVERAL MONTHS AGO THAT THE BYPASS TUBE MAY BE BLOCKED ENTIRELY--
PROVIDED THE NEW STYLE THERMOSTAT HAS A SMALL HOLE IN IT. THE HOLE ALLOWS
SOME CIRCULATION BEFORE THE THERMOSTAT OPENS, PREVENTING HOT SPOTS.
BEN, 54 TF 1500
----- Original Message -----
From: Lew Palmer <lpalmer@mn.mediaone.net>
To: Larry Cogan <woodrat@spacey.net>; Lew Palmer <lpalmer@mn.mediaone.net>;
Stuart Keen <simbafish@home.com>; MG T Digest <mg-t@autox.team.net>
Sent: Thursday, July 06, 2000 3:23 PM
Subject: RE: Thermostat
> I can't disagree with simply "restricting" the coolant flow rather than
> blocking it off completely. It's just that I have been running that way
for
> years with only other non-bypass issues giving me problems.
>
> I only relate what has worked for me here in Minne"snow"ta.
>
> Regards,
> Lew Palmer
>
> -----Original Message-----
> From: Larry Cogan [mailto:woodrat@spacey.net]
> Sent: Thursday, July 06, 2000 4:12 PM
> To: Lew Palmer; Stuart Keen; MG T Digest
> Subject: Re: Thermostat
>
>
> Lew: Im not an expert on this, for sure, but let me relay the essence
> of whats been a recent long thread on the T-ABC list. (Of course the
> XPAG engine is the same in the TC.) Some very smart guys have made
> the point that blocking off the by pass completely is not good, if a
> thermostat is installed. The reason has to do with localized hot
> spots at the rear of the engine which develop because if the bypass
> is totally blocked, there is no coolant movement for a period of time
> before the thermostat opens. The consesus is to place a restrictor
> plate in the bypass with a 3/8" hole in the plate. This then of
> course allows some movement of coolant to take place while waiting for
> the thermostat. Additionally, if the thermostat fails closed, you
> have a much more "benign" temp rise, hopefully allowing you to see the
> problem before meltdown.
> Leave it wide open or put in a drilled plate. Regards, Larry
> ----- Original Message -----
> From: Lew Palmer <lpalmer@mn.mediaone.net>
> To: Stuart Keen <simbafish@home.com>; MG T Digest
> <mg-t@autox.team.net>
> Sent: Thursday, July 06, 2000 4:22 PM
> Subject: RE: Thermostat
>
>
> > Stu,
> >
> > Although Minnesota isn't exactly Florida climate, we do a lot of
> touring in
> > the hot summer months (90 degrees). Here's what I do:
> >
> > 1) I completely block off the bypass. I simply cut a solid gasket
> from a
> > plastic pop bottle and place between the thermostat housing and the
> bypass
> > elbow.
> >
> > 2) I make sure all water passages in the block and radiator are
> clear.
> > Especially prone to blockage are the areas behind the
> expansion/access plugs
> > in the block.
> >
> > 3) I make sure I have the minimum possible amount of clearance
> between the
> > water pump impellor and pump body.
> >
> > 2) I add 1 quart of NAPAKool to the radiator into a 50% mixture of
> > water/antifreeze. (A lower ratio is better (more water than
> antifreeze), but
> > unless I want to constantly change mixtures during the year, I can't
> because
> > of freezing temperatures during the cold months.)
> >
> > 3) I drive with no concerns.
> >
> > I am only using a stock, modern thrmostat (don't remember the
> number, but it
> > is a 165 degree unit) that fits the opening.
> >
> > And, yes, water flows from the engine into the top of the radiator
> and out
> > the bottom. (Remember, hot water rises, cold water sinks). This
> gives an
> > assist to the water pump because of thermosyphon action. Many
> pre-war MGs
> > never even used a water pump, relying solely on thermosyphonic
> action.
> >
> > Regards,
> > Lew Palmer
> >
> > -----Original Message-----
> > From: owner-mg-t@autox.team.net [mailto:owner-mg-t@autox.team.net]On
> > Behalf Of Stuart Keen
> > Sent: Thursday, July 06, 2000 2:54 PM
> > To: MG T Digest
> > Subject: Thermostat
> >
> >
> > The original thermostat in my 1951 MGTD MKII is defective and a
> similar
> > type is no longer available. What should I do? Please bare with me
> as I
> > explain in somewhat detail; history and what has been done to date.
> >
> > When I purchased the TD, the thermostat was the removable type, it
> had a
> > center brass bolt which bolted to a cross arm in the upper parts of
> the
> > housing. The bolt was affixed to 1) a 1 7/8 inch diameter, 5/8 inch
> high
> > brass band (which affected the flow in the bypass tube) and 2) to
> the
> > thermostat diaphragm. The bottom of the diaphragm was bolted to a 2
> inch
> > diameter flat ring via three supporting arms. This lower ring fitted
> > into a grove in the housing. To install, the thermostat was inserted
> > through the bottom of the housing until seated and the top bolt was
> > inserted in the crossarm and the nut tightened.
> >
> > The thermostat was inoperative when I purchased the car. The
> previous
> > owner had soldered the diaphragm in the compressed (open) condition,
> > saying that driving in Florida, the thermostat would be open all the
> > time anyway. He emphasised the need for some restriction in the
> water
> > flow path.
> >
> > When the engine was rebuilt in January, the machine shop saw the
> > soldered thermostat and junked it; ie. returned the TD with no
> > thermostat installed. I have the old thermostat but it is in pieces;
> i.e
> > butchered.
> >
> > Being advised I should not drive the TD without a restriction in the
> > water flow, I ordered a thermostat from Moss (also tried Abingdon,
> but
> > they had none available). The Moss thermostat was completely
> different,
> > just a flat circular plate with a small thermostat system protruding
> > from the center. The replacement fit loosely in the grove in the
> bottom
> > of the thermostat housing, so I flattened the raised edge to make it
> > more snug.
> >
> > I am concerned about the thermostat since I am about to make a 5,000
> > mile trip in the TD. I was about to order a housing with
> non-removable
> > thermostat from Moss, but would like advice first to know if this
> > expense is really necessary.
> >
> > Last night I read over 200 archived messages about thermostats. The
> > common thread is that you should have some restriction in the bypass
> > outlet. The original unit provided this with the brass band, but the
> > Moss replacement does not provide any restriction. Is control of the
> > bypass really necessary if I am driving in a hot climate all year?
> >
> > I ask if it is really necessary because I have now driven approx
> 4,000
> > miles with the Moss replacement thermostat installed and with no
> > restriction in the bypass outlet. Much of the driving has been in
> > Florida, but even here my water temperature gauge (rebuilt several
> > months ago by MoMa) never registers higher than 83 deg C, usually in
> the
> > mid to high 70s. The water temperature seems to be okay, so should I
> > even be worrying about the quasi thermostat installation in my TD.
> Am I
> > just being a perfectionist and a worry wart?
> >
> > I am not even sure I installed the replacement thermostat correctly,
> but
> > it seems to work. The unit is marked with the words "TOP" on the
> ring,
> > with the spring and housing protruding below. This is how I have it
> > installed. However, there is an annotation on the side saying "Flow"
> and
> > an upward arrow. What is the direction of water in the system? Is
> water
> > coming from the top of the engine, UP into the thermostat housing
> and
> > then into the top of the radiator to cycle downward and be cooled.
> For
> > some reason I thought it was the reverse. Shows how little I know
> about
> > cars.
> >
> > I am listening to all advice, such as
> >
> > 1) leave well enough alone, the water temperature seems to be okay
> now
> >
> > 2) order a housing with non removable thermostat from Moss
> >
> > 3) put some kind of restriction across the bypass opening as
> suggested
> > by some of the archives.
> >
> > Thanks for your patience in reading all this detail, for putting my
> mind
> > at ease and for any suggestions.
> >
> > Stu Keen
> > Venice, Fl
> > simbafish@home.com
> >
> >
>
>
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