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  #31  
Old 15-08-14, 00:28
Lynn Eades Lynn Eades is offline
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Andrew just something to consider. there is a rudimentary seal under the pump diaphragm. Can I assume you have not checked it. The seal supposedly stops oil getting through to the under side of the diaphragm from where it exits at the breather hole (in the bottomside of the pump casting. It has to have the hole. I do think your main problem is not here though.
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  #32  
Old 15-08-14, 04:20
rob love rob love is offline
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Too bad you can't affix an elbow and a small tube so the oil dumps deeper in the tube, below the fuel pump.
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  #33  
Old 15-08-14, 09:55
andrew honychurch andrew honychurch is offline
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thanks Guys. I stripped it down again yesterday and have identified the oil leak to be more due to the seal between the aluminium pump mounting and the top of the inlet manifold where the pump pushrod emerges. there is a tube pushed into the manifold aperture here and it sits slightly proud causing a bad seal to the aluminium pump manifold. I have mad up a new gasket and applied RTV sealant so am hopeful this will hold back the weeping oil leak which was gradually messing up my hull floor!

I am still slightly surprised that the oil flow seems to be fairly constant through this PSV. Its a while since I applied my mind to this so will need to recheck everything, such as whether I have the flow path the correct way around for the oil cooler lines. I am sure its correct as I would have checked this before. I guess I was hoping somewhere out there is a modification sheet detailing the fitment of this PSV and explaining the operation. I am planning on driving it about 5k today to go to Combined Ops at Headcorn ( will have both the Lancasters displaying over the weekend should be amazing sight) and this should be a long enough drive to open the oil cooler thermostat which would then reduce the flow through the PRV.
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  #34  
Old 17-08-14, 20:43
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Quote:
Originally Posted by andrew honychurch View Post
I am still struggling to work out why the British army modified the PRV set up as per mine on the above photograph. I have seen one other T16 with this set up, again ex British Army.
It's certainly a brain teaser Andrew. I'm not familiar with carriers but here's my conclusion based on Ford CMP background. The PRV installed on your T16 is set up to reduce to engine oil pressure, which can serve only one possible purpose, namely oil cooler protection. Presumably they were prone to fracture, which is certainly to expected in copper pipe subject to flexing and vibration, which leads rapidly to hardening and fatigue crack formation. Copper pipe has long since been abandoned in vehicle applications for that reason. Flexing in oil cooler pipes would be induced by constant oil pressure variation, eg. start up and shut down as well as gear changes. Pipe bends are particularly subject to flexing, especially a 180 degree return bend if present, which I assume to be the case in carriers. Flexing force can only be reduced by pressure reduction, hence PRV installed by the British. Same principle applies in domestic plumbing to reduce "water hammer" by installing PLV (Pressure Limiting Valve).

Of course, we still have to explain why only the T16. Once again I'm not familiar with carrier production, but the possibility of such a mod only exists on the post '44 flathead, which ran 70 psi with the PRV in the oil pump itself, replacing the early type oil pump which ran 40 psi using the PRV in the front of the block. I should state here that I've never seen the 70 psi spec written anywhere except on the plate pictured below, which is occasionally found on Australian late production Ford CMP dashboards, ie. mid '44 onwards. However the early production dashboard, ie. commercial type, featured a 50 psi gauge, whereas the late production dashboard, ie. military round guage type, featured an 80 psi gauge. Hence while the plate itself is extremely rare, the gauges lead to me believe that all post '44 motors ran 70 psi. Certainly this particular T16 motor is post '44 high pressure, as evidenced by 80 psi reading. Once again, the very presence of an 80 psi gauge would indicate that.

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Presumably in carriers the British dropped these motors back to 40 psi or thereabouts, as on pre '44 engined carriers, using an external PRV rather than pull the motor down to perform the necessary internal mods. As such it's a relatively simple mod which would reduce maximum pressure considerably, and could also be expected to deliver more constant pressure, both of which would greatly reduce oil cooler flexing. Meanwhile it presents no problem for the motor, which simply reverts back to pre '44 oil pressure and flow rate, with the excess flow from the post '44 pump being dumped in the breather standpipe. The same location was used for oil return when fitting partial flow filters on early flatheads, except it was plumbed via the LH stud which was drilled for the purpose. Obviously the T16 overflow would be considerably greater, however we can assume it presented no drainage problem in British service.

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The other aspect of the British mod is removal of the 10 psi bypass valve, which acts to reduce cold oil flow to the cooler, by responding to abnormally high pressure due to viscosity. As such it's a rudimentary oil temp regulator, which if my reading of this thread is correct, was replaced by the British with a proper thermostat. At first glance it may be thought unwise to remove the 10 psi bypass valve, which in addition to it's intended function, would also protect the motor in the event of oil cooler blockage. However it can be seen from the carrier manual pages posted by Lynn that no such blockage is contemplated, presumably because no potential for blockage exists in service, owing to the cooler pipes being of far greater diameter than the engine oil passages. In other words, British removal of the 10 psi bypass valve is perfectly safe.

Given the adjustable PRV used by the British you're left with a choice Andrew. You can screw it down tight and let the flathead PRV take over, which will increase maximum oil pressure to 70 psi and eliminate all flow into the breather standpipe. However it may jeopardize the 70 year old oil cooler, which the British evidently believed even when it was brand new. Alternatively you can adjust the PRV to 40 psi to emulate the pre '44 motor, which will offer maximum protection for the oil cooler, but generate constant overflow into the breather standpipe, owing to 30 psi differential across the PRV. Remember you have 70 psi going into the PRV at anything above idle rpm, because it's coming direct from the 70 psi pump (minus a few psi to the rear main bearing only). Of course you can always choose somewhere between 40 and 70 if preferred, and if the original British setting can be retrieved it may provide some guidance.

As others have suggested the PRV needs to be set using a reliable oil pressure guage, meaning a capillary type rather than electric. This can be fitted temporarily in place of the existing sender unit, which despite its proximity to the OUTLET passage is actually connected internally to the RETURN passage, by means of a tapered bushing inserted at the passage intersection. This can be seen on the CMP diagram below, which I assume is identical on carrier motors. Obviously it's the RETURN pressure that matters, since that's what the motor receives. Note 10 psi bypass valve essential in this application, because filters are subject to clogging. Interestingly I've never seen this filter configuration implemented - to the best of my knowledge the early production CMP had no filter, and late production had a partial flow filter, with oil return direct to the sump via an external pipe.

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Another consideration is the oil temp thermostat, and there may be ways of checking its operation. Main thing of course is to confirm reasonable oil pressure through the full temperature range, allowing for the expected drop at full operating temp on worn motors.

Hopefully the above makes some sense of this puzzling British mod!
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  #35  
Old 18-08-14, 10:21
andrew honychurch andrew honychurch is offline
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Hi Tony, this is a great response and has gone pretty much all the way to explaining the British Army modification. Certainly when driving my T16 back from a show yesterday the engine oil cooler remains cold for quite some time, which is when the oil is being dumped back into the breather tube at full flow and then when it gets to a suitable temperature it gets hot as the thermo valve opens. You are of course quite correct that it still does flow into the breather tube but at a reduced rate and is not such a problem. I could alter the pressures again as you so expertly explained in your reply but I am of the opinion that someone with greater engineering expertise than me has decided on the pressure it is set at and sealed the PRV with a lead seal so who am I to alter it. I have managed by improving the seal on the bottom of the fuel pump manifold/housing to stem the flow of oil, and what little is finding its way down the side of the bell housing onto the floor will help stop rust! I also had a pm from another member of MLU who pointed out a memo, and I copy it here

15 April 1944.
Pamphlet (Provisional) for Battalion Introduction to T.16
Modified for 4.2" Heavy Mortar

Oil Cooler:
1. The only weakness that has come to light so far with the T.16 is the tendency for the engine oil cooler to burst when the lubricant is cold.

2. This is being corrected by a modification, but in the meantime great care must be exercised when starting the engine from cold in lower temperatures. The engine should be started and allowed to idle for a period of from 3 to 5 minutes to warm the oil, and under no circumstance will the engine be "revved up" during this period.


so thank you both very much for the input to this issue, and now its here on the forum will hopefully help other owners who may wonder why this was done.

Andrew
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  #36  
Old 19-08-14, 16:55
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Fabulous to see the '44 memo Andrew. Wartime directives add so much to our understanding and appreciation of military vehicles and their history. This one is particularly interesting and useful for owners as you say. Evidently the 10 psi bypass valve did not provide sufficient pressure relief with the 70 psi motor when cold. The same issue would arise for early carrier owners fitting a post '44 motor, and such owners may be wise to follow the advice in this memo concerning cold start up. Adjusting the bypass valve to less than 10 psi would seem like the obvious solution, and presumably the British tried that initially, but the limitation then becomes the passage through the valve, which is quite small and probably insufficient to allow cold viscous oil to flow fast enough to cope with the extra 30 psi produced by the post '44 motor - thus giving rise to greater than 10 psi pressure drop through the cooler, with the attendant flexing stress that would cause, concentrated at the return bend. Furthermore, adjusting below 10 psi would lead to bypass flow when the oil is hot, thus greatly reducing flow through the oil cooler when it's most needed. The next solution would be to fit a higher capacity 10 psi bypass valve, which would cope with the required flow when the oil is cold and viscous, without effecting flow through the cooler when hot. However, while that would certainly keep the pressure drop through the cooler pipes to no more than 10 psi, it would not reduce the ABSOLUTE pressure within the cooler pipes, and it's this ABSOLUTE pressure which the British seemed intent on reducing, to somewhere below 70 psi. Perhaps they considered the potential existed for coolers to burst at normal operating temperatures also, and sought to guard against that possibility. However it's also true that by utilizing less than the full 70 psi pump output the pressure would be more constant through the rpm range, as the pump is always operating well within its capacity. In other words the external PRV is not only reducing absolute pressure in the cooler pipes, it's also dampening surge pressure, eg. during gear changes. As such it's a very well conceived mod IMO, which I'd expect to provide excellent protection for the oil cooler, superior even to the the standard 40 psi system.

It's also clear the British were intent on improving oil temperature control, otherwise they would have simply left the 10 psi bypass valve in place, rather than go to the trouble of fitting a thermostat. This is a vast improvement of course, particularly in cold climate use. Note however that British removal of the 10 psi bypass valve means ALL the oil to the motor must pass through the oil cooler first. That would explain why your oil cooler remains cold for so long Andrew - it's the engine oil itself which is remaining cold. In other words the cooler is cooling the engine oil unnecessarily. That can't be avoided as there needs to be sufficient flow to the motor at all times, which means the thermostat installed by the British must NOT restrict flow excessively when cold. That makes it even more important to fit thermostats in the heads, otherwise the oil will take far too long to reach operating temp, causing extra wear in the motor. Optimum oil temp is 220F or thereabouts, to drive off moisture accumulation due to crankcase condensation, and provide optimum viscosity for lubrication, and such temps cannot be reached until the motor itself reaches full operating temp. Of course if the oil cooler thermostat is stuck fully open it would exacerbate the problem, and this would be worth checking in due course. Firstly however you need to ensure thermostats are fitted in the heads and operating correctly.

Given that ALL the oil is flowing through the cooler at ALL times, the INCREASED flow observed into the breather standpipe when cold is explained by REDUCED flow through the motor when cold, due to oil viscosity. When the oil heats up and gets thinner it will flow through the bearings much faster, thus reducing overflow to the breather standpipe. Once again this another reason to ensure thermostats fitted in the heads, as it will greatly reduce the duration of high oil flow to the breather standpipe.

It's worth noting in this discussion that modern multigrade oils do not present viscosity problems when cold, certainly not to the same extent as single grade wartime oil, which in severe cold required dilution with fuel prior to next start up. I believe this applied also in desert use, due to cold overnight temperatures, with high daytime temperatures precluding the use of 10 SAE grade engine oil.

I agree with you concerning British PRV setting, certainly that would be my own preference in this situation, for the reasons you mention. As you say they had the expertise and no doubt consulted Ford on the question, plus they were able to trial in service. I'd be interested to see what pressure it runs at full operating temp, seems likely to me they would have chosen 50 psi or thereabouts, rather than drop it all the way back to 40 psi like the pre '44 motor. The memo suggests it was only a cold start up problem, and they'd be seeking to minimize overflow to the breather standpipe at normal operating temp, no more than necessary to solve the cold start up problem. Of course it's possible the use of modern multigrade oil would be sufficient in itself to solve the problem, and allow you to run the full 70 psi, but why take the risk, especially in your cold English climate! It is after all a 70 old oil cooler with a known tendency to burst during cold start up even when brand new.

Once again a fascinating MLU thread which has furthered my carrier education, which I confess is sadly lacking!
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  #37  
Old 22-06-17, 23:45
Colin Alford Colin Alford is offline
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Andrew,

I realize that I am resurrecting a very old thread but I stumbled upon these documents that I believe relate to your Oil Pressure Relief Valve.

There is mention of the modification in "Carriers -Minutes of the 4th meeting held at D.T.D. Chobham on 11th July, 1944" located at this link: (images 3348 - 3356) (I have also attached an image)

http://heritage.canadiana.ca/view/oo...5779/1?r=0&s=1


There is a test report on "Cold starting test on pressure relief valve for oil cooler of T 16 carrier, developed by the Ford Motor Co"

Located at this link (images 3432- 3442):

http://heritage.canadiana.ca/view/oo...5779/1?r=0&s=1

I have not tried to analyze the issue to determine if your system is operating as intended.

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  #38  
Old 23-06-17, 14:31
andrew honychurch andrew honychurch is offline
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hi Colin, thats a great find, and I am sure its exactly what I have on my T16, hence its total absence from the parts book or the TMs. Was there more than the page you photographed as I could not get the pdf on the link, so just read your one page? many thanks indeed andrew
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  #39  
Old 23-06-17, 20:52
Colin Alford Colin Alford is offline
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Hi Andrew,

In the "Carriers - Minutes of the 4th meeting..." document the only mention of the modification is the section that I copied and posted an image of.

The "Test Report" is a ten page document with text and charts and I am not sure if I can copy it at sufficient resolution to post it here.

My suggestion is to try the link again. You should not need to download a pdf. The link should take you to an online file titled: Canadian Military Headquarters, London : C-5779. The file has 4873 images that are a digitization of a microfilm taken of files held at Library and Archives Canada. If you click on the drop-down "image #" and then scroll to the previously quoted image numbers, you should be able to see the document.

I hope this helps. Let me know if you are unsuccessful and I could copy the entire Test Report and send it to you via email.

If you are successful then you can then have the pleasure of spending far too many hours scrolling through the other associated documents in these files.

Colin
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  #40  
Old 23-06-17, 21:20
andrew honychurch andrew honychurch is offline
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ok, I now seem to have to managed to view the files, as you say there are a lot to get through. I will persevere until I find the article. Good stuff though. well done for finding this. Would be good to have an archive on here perhaps!?
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  #41  
Old 25-06-17, 09:19
Lynn Eades Lynn Eades is offline
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I'd like to know the origin of Andrew's By Pass Valve shown in the first photo of this thread.
What is the date on the valve and the makers name please?

I have seen one of those valves here in N.Z. I have heard there is a T16 here, but not seen one. They are at least very thin on the ground here and am now surprised that it might be a T16 part.

Of more importance to Andrew:

These Valves are each used in a different fashion.
The four port valve is plumbed in, in parallel and it is the pressure differential between the "in" and "out" that caused the valve to open and bypass.
Either way FULL pump pressure (all of the oil)returns to the block to run through the galleries, to lube the engine. Just not necessarily running via the cooler.

In Andrew's carrier the oil is directed at the cooler, but depending on the setting of the valve, and the flow restriction of the cooler, a percentage of the volume is dumped directly to the sump. This may be too much.
The bypass spring in the four port valve is a relatively light spring and is not designed to deal with full engine pressure.

I assume yours has a heavier spring fitted.(than the four port valve) What ever this valve opens at, dictates the maximum oil pressure to the engine. It is in effect an external oil pressure relief valve, down stream from the one in the pump.
If your electric gauge is accurate, its max reading will likely be the opening pressure of that valve.

You might like to see my thread on setting the std U.C. (four port) valve.
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Last edited by Lynn Eades; 25-06-17 at 09:37.
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  #42  
Old 25-06-17, 21:29
andrew honychurch andrew honychurch is offline
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thanks Lynn. As per my other post, I have been concentrating on an ignition problem, now solved so will take a look at the PRV and see if there are some markings on it. Its a while since I applied my mind to the PRV problem since when I have restored 3 other vehicles! I am sure I solved the leak which was really my only concern. The oil coolers are both getting warm so I am sure circulation is fine. I will try to post up tomorrow. I feel we have learnt a lot about the T16 cooler and its pretty evident that Chilwell developed a retro mod to avoid oil coolers and lines failing through cold viscous oil at start up.
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