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No water circulating to or thru hose leading to Stromberg carburator

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lynasita Avatar
lynasita Lynne Graham
Albuquerque, NM, USA   USA
1975 MG MGB
1975 MG MGB
Car starts , runs fairly well for 10-15 minutes, temperature gauge indicates engine warming. As car warms performance decreases, then stops. Fuel / Air ratio too rich, car will not restart until cool . Removed hose leading to single Stromberg 175-CD-2 carb thermal Äuto-Choke and found no liquid going to assembly. Intend to remove T-Stat and observe flow . Any other suggestions?
Thank you for your assistance!

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course2kid Jeffrey Johnson
Fountain Valley, CA, USA   USA
1979 MG MGB "Lucy (Lucifer)"
Possibly air in the cooling system, water pump turbine disconnected from water pump shaft, or belt slipping on water pump pulley.

I doubt it is a problem with the water jacket on the ZS carb because that has a fairly large flow passage and it would be very difficult to clog it.

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MG47484 Mike B
Lima/Aston, PA, USA   USA
1963 Chevrolet C10 "My White Work Horse!!" ~ For Sale ! ~
1975 MG Midget MkIII "Young Marine’s Weekend Pass!"
2005 Nissan Frontier V6 4WD "The Silver Ghost"
2009 Subaru Legacy "Wife's Slave"
WEBER CARB and Headers!

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ClayJ Avatar
ClayJ Silver Member Clay Johnston
Mt. Olive, MS, USA   USA
1972 MG MGB
You may need to remove the boss that the hose attaches to on the back of the head, clean port and fitting and reinstall. Make sure you have a gasket before removing.

It also sounds like your choke might be maladjusted or malfunctioning.

Seems with the ZS carb, if anything goes wrong they go VERY rich.

course2kid Jeffrey Johnson
Fountain Valley, CA, USA   USA
1979 MG MGB "Lucy (Lucifer)"
Sorry, my above answer was far from complete - as Clay points out, it may be that you do have water circulating and that the autochoke is just malfunctioning.

First thing to check on the autochoke is to see if the three copper slotted screws that secure it to the carb are tight. If they aren't then tighten them and see if that cures the problem.

If the problem still exists, you'll probably want to rebuild the autochoke as shown in the attached John Twist videos (complete carb overhaul including the autochoke) or as described in the pdf file in the attached link. Unfortunately, neither the videos nor the pdf list the sizes for all the O-rings in the autochoke and carb. The Moss catalog also doesn't show the o-rings for the autochoke. When I rebuilt my carb and autochoke, I bought a variety of o-rings online from a place in Seattle called "The O-Ring Store" and just used the sizes I needed, unfortunately (and stupidly), I failed to write down all the sizes I used. So, if you rebuild, please record which sizes are used and post them on this site for the benefit of all! NOTES: 1) As I recall, I bought Viton O-rings wherever possible, and, if a size needed wasn't available in Viton, then I bought BUNA N O-rings. 2) O-rings are pretty inexpensive and weigh next to nothing, so, it makes sense to buy a few of every size you might need and combine them in one order to save on shipping 3) In the JT videos, he does not remove the enrichment needle sleeve to replace its o-rings as shown in the pdf, and 4) When reinstalling tge enrichment needle sleeve, if you press it all the way in until it bottoms in the bore of the autochoke housing, it may go in too far and limit the motion of the autochoke cam such that the fast idle cannot go all the way off. Since I'm only allowed four attachments per reply, I'll post a pic in another reply so that you can see what I mean.






http://www.sterlingbritishmotoringsociety.org/files/choke.pdf

course2kid Jeffrey Johnson
Fountain Valley, CA, USA   USA
1979 MG MGB "Lucy (Lucifer)"
Here is a pic of the autochoke with the fast idle rotated fully off. Note the fairly small gap between the cam and the plastic pin. On my choke, when I pressed the enrichment sleeve (brass tube at the 6 O'clock position fully in, the enrichment needle would bottom out before the cam could rotate fully CCW, and the fast idle cam could not fully disengage, so, I had to drive the sleeve back out a bit to get the small clearance as shown in the picture.



Edited 1 time(s). Last edit at 2017-10-09 02:26 PM by course2kid.


Attachments:
150757706611973418467.jpg    35.2 KB
150757706611973418467.jpg

lynasita Avatar
lynasita Lynne Graham
Albuquerque, NM, USA   USA
1975 MG MGB
1975 MG MGB
Clay,
Thank you for your post; I have not detached that end of the hose . Was not aware of the boss or the gasket.
Thanks for the heads up!

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lynasita Avatar
lynasita Lynne Graham
Albuquerque, NM, USA   USA
1975 MG MGB
1975 MG MGB
Doctor Clay J,
What a wealth of information!
I will gladly record and post O-rings used if it comes to that.

Removed T-stat, elevated the car to accommodate anti-freeze collection,
Started and witnessed coolant flowing out the " Auto -Choke", boss passage at rear of the engine appear to be unobstructed.
Reconnected line and ran like a thoroughbred. Would rev,hold for 15, and it responded well on Deceleration and purred at idle.

Lowered the car and it won't start ; Go Figure.
Any thoughts Doc?

Greatly Appreciative,
Lynne

ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
Now that waters flowing have you inspected the diaphragm in the ZS CARB



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

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lynasita Avatar
lynasita Lynne Graham
Albuquerque, NM, USA   USA
1975 MG MGB
1975 MG MGB
Doctor Jeffrey Johnson,

Read your response , worked on the car, then came up to THANK Everyone and give them
an update on my progress. During that time I got my Johnson's juxtaposed.
The comments in my previous post to Clay were written with your comments in mind.

Your information, advice,pictures and links to other valuable resources is the new "awesome"

Greatly appreciative ,
Lynne

lynasita Avatar
lynasita Lynne Graham
Albuquerque, NM, USA   USA
1975 MG MGB
1975 MG MGB
Rob,
I have not been into the Carburettor yet, Since it was running so rich after warming; I wanted to determine at least a flow thru the device.
Now I am trying to understand how it ran phenomenally when the front was elevated. Had I had a different pan I would have never had an opportunity to observe the difference.

Thanks for your comments.

Lynne

ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
Running rich in a zs is comoon to a few causes. One of the, being a torn diaphragm.
Also nearer use starting ether in a zs carb.



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
Running rich in a zs is common to a few causes. One of them being a torn diaphragm.
Also never use starting ether in a zs carb it destroys the diaphragm



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

course2kid Jeffrey Johnson
Fountain Valley, CA, USA   USA
1979 MG MGB "Lucy (Lucifer)"
Lynn, When you raised the car and it then ran well, did you raise the front, rear, or both ends of the car? If you raised just the rear, this may have increased fuel pressure to the carb a bit.

Other than that, I'm at a loss why raising or lowering the car would affect its running.

If you raise it back up again, does it run well once more?

Also, when you say that it didn't run once you lowered the car - what exactly did it do? Would it crank? Would it fire, but stall immediately? Would it run, but very poorly? Any such additiinal information might be a useful clue in diagnosing the problem.



Edited 1 time(s). Last edit at 2017-10-10 01:45 PM by course2kid.

ClayJ Avatar
ClayJ Silver Member Clay Johnston
Mt. Olive, MS, USA   USA
1972 MG MGB
As Jeffery notes, more information on it's current behavior would help.

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