Mike C
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Posts posted by Mike C
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2 hours ago, John McCormack said:
Thank you all.
I have filled the tank as it was a bit low and it immediately seems to be starter better. Back to a couple of short cranks.
I thought it might be possible that the fuel level in the injection pipes dropped a bit with a low tank level. I am not sure how this might happen but in my mind it was a possibility. I am chasing an old metering unit to dismantle and see exactly how they work.
I will check the plugs, haven't done it for a long while. I should do a tappet check as well. I believe in 'if it ain't broke don't fix it'. But they might need a bit of a clean and adjustment.
You might have had stale fuel previously?
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I used to like vegetable based oils- there was nothing like the smell of Castrol R and methanol on a good day.
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I'd believe most TR6 owners would accept starting after 2-3 cranks to be pretty a good result.
I don't believe the slightly longer cranking duration would be caused by a clogged fuel filter. The fuel demand when cranking is fairly low- clogged filters normally cause problems at high speed/high fuel demand.
Have you checked the adjustment of the enrichment lever on the MU?
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I replaced mine years ago, one thing I do remember is that the rubber kept shrinking for about two months- I had to fabricate a new joining chrome strip for the bottom.
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11 minutes ago, charlie74 said:
If rings wouldn’t the marks go the whole length of the stroke? It’s hard to tell in the photos…
The original piston insertion process might have included twisting the pistons, possibly someone that didn't use a good ring compressor. That's about the only process I can think of that will cause the limited helical scratches over the honing.
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That looks like the piston ring ends scratched the bores during the last assembly , after honing. Buy why all 6 ?
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1 hour ago, john.r.davies said:
How much blow-by do you have?!
And, is the can trapping much oil?
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What did the one way clutch look like on the end of the splined shaft?
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I'd disconnect the ends of the brown wire and find out where it's earthing with a multimeter.
Some earthing points may be due to burnt insulation but one earthing point probably caused the original fault.
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3 hours ago, M2 competition said:
Thanks Mike no it’s good all overdrive I review all and it works all the overdrive only that slips in reverse if you put the car with the wheel in the air reverse works but you put in the ground and fonts works reverse and the clutch of the overdrive looks good outside and inside
I'm not an expert on J type overdrives, but for those that are you need to confirm-id your OD slipping in reverse when it is disengaged.
A photo of your unidirectional clutch would help the experts assess its condition.
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Your overdrive slips in reverse? If it's engaged in reverse you've probably broken the unidirectional clutch.
I had a wiring fault with my A type and the car was put into reverse with the O/D engaged it kicked like a mule.
When you dissembled the O/D did you notice broken pieces of metal or metal flakes? They may be clustered around the magnetic drain plug, if you have one fitted.
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Won't fully closing the butterflies destroy the throttle body?
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The 90 psi may or may not result in the pump using more power. The power used by each model pump is proportional to the flow and pressure- if your pump pumps more petrol at 90 psi it could well use more power-the higher petrol volume will keep the pump cooler but the higher power input will warm up the tank faster.
My fuel pump is an ancient Bosch 0580254957- user's of your model pump could give you a better idea of what settings will best work with it.
The Lucas Red Book says that the injectors should start to open between 45 and 55 psi on their test bench.
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27 minutes ago, PodOne said:
Thanks Clem
The smell of petrol has shrivelled my grey matter!
The return was clear.
Lots of questions anyone as ever.
1) Why the difference in psi requirements between the Lucas (100 -110psi) and the Bosch (90psi) pumps as measured at the MU?
2) Am I right in thinking the Bosch flows better than the Lucas at higher rpm enough to "pop" the injectors faster/longer ?(which open at what psi?)
3) What's the problem running the Bosch at a constant 100-110 psi which is the same a OEM spec Lucas set up?
I see Moss sell a PRV to go with their Borsch pump but don't state its set pressure.
Andy
The MU and injectors can't tell if they are being fed by a Bosch or Lucas pump. Last time I did any calculations on my PI system far more fuel was being returned to the tank through the PRV than used by the MU, even with the engine at full load. The PRV set the PI system operating pressure for all load conditions.
Each model of Bosch pump has a different pump performance curve. If you set the pump to run at , say, 110 psi you need to check that your pump has adequate flow at this pressure to allow sufficient internal pump cooling- ie if your pump just makes 110psi at close to zero flow it will overheat.
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On 12/12/2023 at 6:40 PM, elclem1 said:
For a bosch pump i set mine to 90 psi. Never had a problem with that.
Disconnect the leak off from the mu and blow some air into the tank return line - you'll hear it enter.
I had the rubber go inside the mu the symptoms were fuel leaking from the mu plastic cover when the fuel pump was running, changed it and it was sorted. Neil Ferguson was my go to person for the spares.
Enjoy sorting out the problems it helps the grey matter i find
Clem
Yep. I've always set my PRV to 90 psi on the bench using compressed air.
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33 minutes ago, Waldi said:
Hi Mike,
I guess only some specialists know the answer to when the Viton membranes became “the standard“ .
But since you were supplied with a nitrile item some 5 years ago, it makes you wonder….
Waldi
Hi Waldi,
When I bought that part years ago there was little mention of elastomer composition. Some vendors were even selling genuine Lucas original parts- which would have been some kind of aged nitrile.
When the part from the UK supplier failed I decided to look around for something better for the application than nitrile- and from previous experience I knew that Viton was much better-so I looked around for someone that used Viton.
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1 hour ago, Waldi said:
Hi Mike,
Your bad experience make me wonder what quality your membrane was made of. I know a car (and there must be many) of which the MU has not been touched for 2 decades. And without issues.Or were MU membranes already made from Viton-B by then?
Waldi
Hi Waldi,
I reckon the diaphragm the UK specialist supplied me was made of nitrile rubber. To most people it's hard to tell the difference between nitrile and viton rubbers, especially as the QA systems used by replacement TR6 component suppliers are fairly primitive.
After this experience I gave up on trusting the usual TR suppliers for critical elastomers. To make sure I had all viton elastomers installed I bundled up the MU and injectors and sent them to a specialist, who I knew used only viton, for rebuilding and recalibration.
I don't know if viton elastomers were used in TR6 PI systems 20 years ago. Certainly viton gaskets and O rings have been used in the petrochem industry for probably 60 years- the RAAF were using it when I started working on their refuelling systems in 1972.
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Probably your MU fuelling diaphragm. About 5 years ago I installed a new one from one of the major UK suppliers and it failed over lunchtime. Everything tested out OK with the PI system and engine starting before lunch, came out after lunch for a road test and fuel was dripping from the MU bleed hole. The engine wouldn't start and the plugs were soaked with petrol.
The problem is that the UK diaphragm was not Viton , and when exposed to Australian high octane unleaded fuels it swelled , the centre hole enlarged , causing leakage around the shaft.
To put it mildly, I was somewhat upset. The diaphragm had cost in the region of $A150 to airfreight to Australia, and we all know how much effort goes into repairing any MU problems and then replacing/retiming the unit.
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I use a soft cover with a sort of furry internal lining. My garage is super dry, my main problem is accidentally scratching the car while I work around it.
A few decades ago I stored the car outside covered with a waterproof cover. Despite putting blankets on the corners the wind on the cover still wore flat spots on the corners if the blankets slipped, and water from the slab underneath the car condensed in the cover causing micro blisters necessitating a repaint.
If you can accommodate the car in the garage permanently keep it there. Don't be tempted to store it outside.
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I've not seen anything like it. It could be limiting the movement of the slave cylinder piston to the top end of the cylinder. Have you tried the clutch operation with the nut removed?
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Bit of an overkill to fix a pump problem.Potential cures for overheating PI fuel systems have been extensively discussed in this forum. I have a Bosch pump fitted on the wheel arch fed buy a Carter booster pump and have has no PI system overheating problems even on 40 deg C days ( not that I drive around as much on extremely hot days now I'm a bit older).
I personally wouldn't do it but if I switched to carbs it would be to Weber's , not SU's, or maybe a totally modern, programmable injection system.
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If the plugs are wet after a failed restart the problem is electrical. Could be something simple like a dry joint in your ignition that's ceasing to conduct when it gets hot.
Burning oil
in TR6 Forum
Posted
I agree with Mick . The compression test figures look OK. Any damage to the oil control rings?