MLU FORUM  

Go Back   MLU FORUM > MILITARY VEHICLES > The Carrier Forum

Notices

Reply
 
Thread Tools Display Modes
  #1  
Old 17-03-16, 23:51
Malcolm Towrie Malcolm Towrie is offline
Registered User
 
Join Date: Aug 2015
Location: Whitby, Ontario, Canada
Posts: 306
Default

An update on the running problems: the distributor shaft was quite badly bent. It had 0.010" runout at the cam. Since the points gap is only 0.014-0.016" this seriously messed up the dwell and timing with big changes on a cylinder-to-cylinder basis as the shaft did a full rotation. The points being set too wide didn't help.

With a good, used shaft with 0.002" runout, and the points set at 0.015", dwell was right on the money and she's purring now.

Malcolm
Reply With Quote
  #2  
Old 18-03-16, 00:09
rob love rob love is offline
carrier mech
 
Join Date: Feb 2003
Location: Shilo MB, the armpit of Canada
Posts: 7,594
Default

Good for you.

When you say "distributor shaft" I take it you are talking about an 8BA engine with the distributor up top? Seems like it would take a lot of force to bend the shaft on either a crab or a divers helmet distributor mounted on the front of the engine.
Reply With Quote
  #3  
Old 18-03-16, 02:29
Malcolm Towrie Malcolm Towrie is offline
Registered User
 
Join Date: Aug 2015
Location: Whitby, Ontario, Canada
Posts: 306
Default

Quote:
Originally Posted by rob love View Post
When you say "distributor shaft" I take it you are talking about an 8BA engine with the distributor up top? Seems like it would take a lot of force to bend the shaft on either a crab or a divers helmet distributor mounted on the front of the engine.
No, this is a divers helmet distributor. And it doesn't take much force at all to bend it when all the parts are stripped off. I chucked the small end in a lathe and measured 0.060" runout at the journal on the other end. It only took a few taps with a soft hammer to get it straight to within 0.002". It's pretty spindly in the middle as you can see but I was surprised how easy it was to straighten. I cleaned the shaft up thinking maybe it was cracked but I couldn't see any.

Some rough handling would have bent it easily.

I bet the last person to set the points must have struggled.

Malcolm

DSC00055.JPG
Reply With Quote
  #4  
Old 18-03-16, 02:34
Lynn Eades Lynn Eades is offline
Bluebell
 
Join Date: May 2003
Location: Tauranga, New Zealand
Posts: 5,541
Default

I think somewhere back there Malcolm confirmed it was a divers helmet type.
How to bend a shaft in one of those, I don't know.
As it was the centre cylinders and one half of the firing order rotation, I think I was headed in the right direction as far as a misfire goes, but can't see really why it had matching low compressions, when comp test pointed toward valves.

Good news that it is sorted!
__________________
Bluebell

Carrier Armoured O.P. No1 Mk3 W. T84991
Carrier Bren No2.Mk.I. NewZealand Railways. NZR.6.
Dodge WC55. 37mm Gun Motor Carriage M6
Jeep Mb #135668
So many questions....
Reply With Quote
  #5  
Old 18-03-16, 02:54
Malcolm Towrie Malcolm Towrie is offline
Registered User
 
Join Date: Aug 2015
Location: Whitby, Ontario, Canada
Posts: 306
Default

Lynn, I should have got into the ignition problem in a separate thread to avoid confusion as it was a totally separate problem. The low compression hasn't gone away!

That shaft wouldn't bend in service but throwing it in a box and then throwing other parts on top of it would bend it easily, based on how easily I straightened it.

Malcolm
Reply With Quote
  #6  
Old 06-02-18, 07:36
Malcolm Towrie Malcolm Towrie is offline
Registered User
 
Join Date: Aug 2015
Location: Whitby, Ontario, Canada
Posts: 306
Default

An update: due to the low compression test pressures reported at the beginning of this thread, we just pulled the engine to find the cause. I've only got the heads and intake manifold off so far, but checking each valve when fully open, I can see damage to the exhaust valve seats of the 4 low pressure cylinders. That seems to be the culprit. The other exhaust valve seats look ok, so I'm not sure why these particular seats went bad. Tappet clearance too tight and holding the valves off the seat perhaps?
The cylinders are 0.015" over and a bore gauge check of the bores just above the pistons at BDC and at the TDC wear "ridge" shows wear in the 0.002 to 0.003" range for all cylinders, so acceptable, IMO. But even the 4 "good" cylinders only had 85 to 95 psi results instead of 110 psi, so I think the bores need honed and new rings installed.
The valley shows a depressing amount of sludge on all surfaces. And the oil pan has a good layer of black sludge on the bottom. We use a 15W40 diesel oil in most of our vehicles. This is a high detergent oil and I suspect it is bad news in this type of application as the detergent dissolves the stable sludge deposits and circulates it around the engine. We should be using a non-detergent oil on these old engines.
I also found a water pump with the bearings almost seized, front crank seal rope packing installed so tight, it had burnt the paint on the timing cover, causing a severely scored front pulley sleeve, and a crack in the block around the rear boss for the oil cooler supply, due to overtightening the fitting. I'm not sure how to repair that. All in all, a typical 75 year old engine.
Malcolm

Last edited by Malcolm Towrie; 06-02-18 at 07:46.
Reply With Quote
  #7  
Old 06-02-18, 08:15
Lynn Eades Lynn Eades is offline
Bluebell
 
Join Date: May 2003
Location: Tauranga, New Zealand
Posts: 5,541
Default

Malcolm, What model is the engine? What casting numbers if any? Does it have domed pistons? What cylinder heads does it have? What bore size? (just checking)
__________________
Bluebell

Carrier Armoured O.P. No1 Mk3 W. T84991
Carrier Bren No2.Mk.I. NewZealand Railways. NZR.6.
Dodge WC55. 37mm Gun Motor Carriage M6
Jeep Mb #135668
So many questions....
Reply With Quote
  #8  
Old 06-02-18, 20:54
Malcolm Towrie Malcolm Towrie is offline
Registered User
 
Join Date: Aug 2015
Location: Whitby, Ontario, Canada
Posts: 306
Default

Quote:
Originally Posted by Lynn Eades View Post
Malcolm, What model is the engine? What casting numbers if any? Does it have domed pistons? What cylinder heads does it have? What bore size? (just checking)
Lynn, yes, it has domed pistons. CR is 6.12:1.
Stock bore size is 3 1/16", 3.0625". This one is 0.015" over so 3.0775".
It's the 85 HP, 221 cu. in engine. I'll get some casting numbers.

Malcolm
Reply With Quote
  #9  
Old 06-02-18, 20:06
Richard Farrant's Avatar
Richard Farrant Richard Farrant is offline
Registered User
 
Join Date: Feb 2003
Location: Kent, England
Posts: 3,641
Default

Quote:
Originally Posted by Malcolm Towrie View Post
The valley shows a depressing amount of sludge on all surfaces. And the oil pan has a good layer of black sludge on the bottom. We use a 15W40 diesel oil in most of our vehicles. This is a high detergent oil and I suspect it is bad news in this type of application as the detergent dissolves the stable sludge deposits and circulates it around the engine. We should be using a non-detergent oil on these old engines.
Hi Malcolm,
A mistake people often make is getting an old vehicle of unknown history, draining the oil and refilling with a detergent multigrade oil. Most of these old WW2 era engines (and earlier) had either no filter at all or a bypass filter, which was tapped of the oil gallery and returned to sump. Detergent oils keep dirt and carbon in suspension so with a full flow filter system it is quickly cleaned. The older mono-grade oils had no detergent in them and the sludge formed in the sump mainly, so it was flushed out on oil changes. If you get hold of an unknown engine and it has a bypass filter, or none at all, go for a non-detergent mono-grade as blended for vintage vehicles. Actually the Classic / Vintage mono-grades in the UK do now have a very slight detergency in them as I am informed by the oil companies, but they do not scour out all the old sludge like a multigrade does.
Hope I am not teaching you to suck eggs, but I am sure there will be readers who are not aware.
regards,
Richard
__________________
Richard

1943 Bedford QLD lorry - 1941 BSA WM20 m/cycle - 1943 Daimler Scout Car Mk2
Member of MVT, IMPS, MVG of NSW, KVE and AMVCS
KVE President & KVE News Editor
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +2. The time now is 20:42.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright © Maple Leaf Up, 2003-2016