52 replies to this topic

[mrmeds]

the other thing i noticed was the fuel in the float chamber looked distinctly yellow ! is this normal ?

[Tornado99]

the other thing i noticed was the fuel in the float chamber looked distinctly yellow ! is this normal ?

Not ideal but likely just showing some "varnish" residue washing off the interior surfaces of bowl/fuel lines/tank etc. A common situation in old cars. Should not be preventing proper running. 

[cal844]

What oil is in the dashpot? Cap on the dashpot on tight?

Is the needle lined up flush with the piston?

[mrmeds]

What oil is in the dashpot? Cap on the dashpot on tight?

Is the needle lined up flush with the piston?

to be honest havent checked- it was firing up yesterday and saturday after a  3-4 cycles of  system i mentioned above- and i've not disturbed /touched anything except float bowl.

 

Tempted to have another go on weekend after battery is recharged- then give up - its due to go to mini sport for some work to be done around october- so might just get it piggy backed up on a tow truck !

[Tornado99]

 

What oil is in the dashpot? Cap on the dashpot on tight?

Is the needle lined up flush with the piston?

to be honest havent checked- it was firing up yesterday and saturday after a  3-4 cycles of  system i mentioned above- and i've not disturbed /touched anything except float bowl.

 

Tempted to have another go on weekend after battery is recharged- then give up - its due to go to mini sport for some work to be done around october- so might just get it piggy backed up on a tow truck !

 

Dashpot situation should not prevent running. It is only there to smooth out/slow down sudden opening/closing of the carb slide...due to faster throttle opening/closing. This helps reduce big changes in manifold vacuum to give overall better running....car should start & run OK without it working, just not ideal. 

[mrmeds]

could the timing be out- it was running a bit hot recently and quite sooty exhaust- and sounding a bit like a diesel at low idle revs

[Tornado99]

could the timing be out- it was running a bit hot recently and quite sooty exhaust- and sounding a bit like a diesel at low idle revs

Its possible, but you'll need a timing gun to confirm. Might have bumped the distributor to move the timing out of whack, if the clamp is not fully securing it.  I would eliminate the previous suggestions first. 

[mad4classics]

okay- ive had a look at the float and needle - cleaned them a bit- and checked they move freely. Put them back.
Now car wont start -
fires occasionally but just wont go properly .
On the plus side, theres no sign of any fuel leak now despite repeated cranking- last night the fuels started coming out within a few cranks.

Whats the best way of getting it started -tried choke half out , cranking for 15 seconds, then stopping, pump gas a few times then repeat crank, then wait 5 minutes before starting again. This worked previosuly.

If the float needle wasn't previously shutting off fuel correctly the petrol level in the jet would have been correspondingly high causing it to run rich.

Assuming you've reassembled things correctly and nothing else has changed it purhaps needs the mixture resetting. You do say the exhaust has been sooty for a while.

Recharge the battery and use more choke; pumping the gas on an SU does nothing since it doesn't have an accelerator pump. Just give it a small amount of throttle.

Edited by mad4classics, 09 September 2021 - 07:28 AM.

[cal844]

What oil is in the dashpot? Cap on the dashpot on tight?

Is the needle lined up flush with the piston?

to be honest havent checked- it was firing up yesterday and saturday after a 3-4 cycles of system i mentioned above- and i've not disturbed /touched anything except float bowl.

Tempted to have another go on weekend after battery is recharged- then give up - its due to go to mini sport for some work to be done around october- so might just get it piggy backed up on a tow truck !

Dashpot situation should not prevent running. It is only there to smooth out/slow down sudden opening/closing of the carb slide...due to faster throttle opening/closing. This helps reduce big changes in manifold vacuum to give overall better running....car should start & run OK without it working, just not ideal.

My 998 would start but not rev, then die with the dashpot empty of oil. It I'd also weight critical, IME minis need a 20w50 oil in the dashpot.

Just my findings in 10 years

Edited by cal844, 09 September 2021 - 12:52 PM.

[mrmeds]

so....... looked at plugs- very sooty

so gave them a clean

turned the engine with fully charged battery and bingo !!!!!  it started

 

for about 5 seconds... then died again.

 

big cloud of white grey smoke and smell that isnt petrolly- more oily.

 

Managed tis several times, but with less smoke. 

[sonscar]

Have you a mechanical pump?If you have sniff the oil to see if it is petrol contaminated from a damaged diaphragm.Steve..

[Tornado99]

so....... looked at plugs- very sooty

so gave them a clean

turned the engine with fully charged battery and bingo !!!!!  it started

 

for about 5 seconds... then died again.

 

big cloud of white grey smoke and smell that isnt petrolly- more oily.

 

Managed tis several times, but with less smoke. 

 

White/grey smoking indicates coolant in combustion chamber turning to steam out exhaust pipe. Black or blue smoke is oil burning. 

 

Could be a failing headgasket not sealing out coolant. 

 

Do a compression check on each cylinder. 

[mrmeds]

 

so....... looked at plugs- very sooty

so gave them a clean

turned the engine with fully charged battery and bingo !!!!!  it started

 

for about 5 seconds... then died again.

 

big cloud of white grey smoke and smell that isnt petrolly- more oily.

 

Managed tis several times, but with less smoke. 

 

White/grey smoking indicates coolant in combustion chamber turning to steam out exhaust pipe. Black or blue smoke is oil burning. 

 

Could be a failing headgasket not sealing out coolant. 

 

Do a compression check on each cylinder. 

 

 

it has been loosing coolant with no obvious puddles- i think its time to give up and wait for replacement half engine to be built ! Should be ready in 4-6 weeks

[mrmeds]

checked oil today to look for signs of coolant- found signs of petrol!- Oil has gone very thin and level in sump is way above minimum . So fuel pump may now be knackered ! 

[Tornado99]

checked oil today to look for signs of coolant- found signs of petrol!- Oil has gone very thin and level in sump is way above minimum . So fuel pump may now be knackered ! 

Unsure how a bad fuel pump leads to oil in sump? Is this a mechanical type pump fitted to the engine block or later e-pump under the fuel tank like my '88?

 

Fuel in oil typically results from poor combustion/combustion chamber flooding and fuel getting past the piston rings into sump.