hmmm
The problem has been very complex and has had varying symptoms - all of which
happened at a similar time. We have narrowed down potential issues and
eliminated things along the way.
The problem itself has shifted slightly in symptoms. I guess we could say
that there have been two things producing similar issues - one was definitely
related to slip and the other is about power loss (not a drop or obvious
lack-but an intermittent problem whereby under full throttle the rev counter
would get to a certain point and then not want to go any further - sometimes
nudging a few hundred rpm or so in a rhythmic slow pulse/waving) other times
we can wrap it around to about 5700RPM quite happily and it pulls with a
vengeance. The problem has changed slightly over the past few months since it
occurred.
So to give you the full picture I'll start over.
--
I installed a new vacuum advance unit (and for the next 50kms or so of driving
experienced no problems). After this point I put the car in to have the
gearbox rebuilt and a juddering clutch fixed.
Whilst having the work done on the gearbox it was found that the overdrive
needed to have a new sliding clutch member fitted. Seeing as we had gone this
far we also lightened the flywheel - fully rebuilt the overdrive and gearbox -
rebuilt the diff and fit the new clutch.
Everything seemed sweet for about 100km then I noticed a slippage at highway
cruising speed in overdrive.
About another 100km later the slippage at high speed could not be made to
happen - BUT - then we noticed when working through the gears vigorously that
we were able to get a slip happening at 4000RPM and above in 1st and 2nd gear
whilst under full throttle. The exact RPM where the problem occurred has
always varied but has always been over 3000RPM . I figured it might have been
only occurring in lower gears so I found a back road and aimed to hit the
highest revs I could in 3rd overdrive. God knows what speed I actually got it
up to (haven't got a ticket yet) but somewhere past 4500RPM or so I got a
problem where it didn't seem to slip but it would not go past a certain rev
point (no rev limiter in my car either and we had plenty of grunt to go).
So we inspected and adjusted the clutch (assuming slip of the new clutch) and
the problem didn't go away.
Then we stripped the overdrive and checked for any contamination that may have
gotten in during the rebuild. Everything was fine (we checked pressure and
operation of the solenoid) so it was put back together and we found issues
again.
We checked the clutch again and no slipping was occurring there. Whilst at it
we fit a larger bore slave cylinder to the box to make things a bit better
under foot.
We investigated the problem a little further with O/D experts and found that
the sliding clutch member in the O/D unit takes up to a 1000km to bed in
seeing as the angles of the surfaces are potentially different and need to
'bed in'.
So we let the problem go for about another 800km (thus clocking up 1000KM) and
found that the problem had not gone away.
It was at this point that we realised something different was happening to
what we originally had which was definitely slip.
The engine was no longer slipping like it was in water (i.e. rev counter no
longer bouncing around towards the red with no increase in speed like it first
did). We found that the problem had now shown itself as a lack of will to rev
any further than a certain point although sometimes it would rev a little
further and come back down again just as if I had my foot mostly down on the
accelerator holding it at a certain rev and then nudging it a little bit. It
feels like someone has stuck something under the accelerator pedal
temporarily. - shift up a gear and stomp on the accelerator and away she goes
again like nothing was wrong.
So the problem is no longer a slip problem.
The problem is worse when the engine is warm and has never happened when the
engine is cold/cool. Obviously I am reluctant to start the car from cold and
immediately boot the hell out of it at full revs like a mad man to see if the
problem occurs. As soon as the engine temp gauge goes close to the quarter
mark it seems to start to show itself.
Anyway, the local Triumph expert has checked the fuel pump for me and claims
that it deliver 2psi which according to him is not enough and he reckons it is
definitely my problem. I disagree, as that seems to be a sensible amount of
fuel pressure.
I have not yet changed the fuel pump but will do so in the next few days. I
tend to think that it is more likely to be related to distributor advance
problems (note above that I had fiddled with parts of the dizzy before all the
other work). We have thought that perhaps float bowl issues were present and
have not yet checked that.
My plan of action is:
Remove / plug vacuum advance.
Check timing and amount of advance that occurs through rev range.
Lubricate distributor components.
Set points gap.
Change Coil and Condenser.
Pull carb suction chamber covers off and lubricate carb pistons.
Thanks to everyone for their help.
----- Original Message -----
From: Pete & Aprille Chadwell
To: Glen Johnson ; Triumphs Mailing List
Sent: Wednesday, January 16, 2002 1:10 PM
Subject: Re: Help needed with Fuel Pump pressure ??
Glen wrote:
>This is interesting. I have noticed that when the engine is colder (after
a
>start or letting it sit for an hour or two then getting back in for
another
>drive) the slipping/starvation/timing problem is not present. After at
least
>15-30 minutes of hard driving the problem returns.
And originally, Glen wrote:
>At high revs in all gears I intermittently get a drop off in
>power that feels as if my wheels are slipping in water.
When I read your first post, this sentence struck me as odd, because
it seems to imply slippage, yet the rest of your message seemed to
point to a 'real' power loss. Plus, you noted that you just
installed a new clutch, so I quickly concluded that the English
language just wasn't serving us all that well at the moment, and that
you were experiencing an engine problem of some sort.
But your most recent post mentions slipping again and so I think we
need to re-examine what the car is doing. If you have fuel
starvation, the engine should suddenly sort-of 'gasp' and then all
power is gone and the engine is no longer running. I have had a
clogged-line problem before (Datsun B210) that was intermittentS it
had to do with sediment in the tank that had been stirred up. After
the car sat for a time, you could drive it again, but eventually the
sediment would clog the line again and the car would gasp and lurch
when you put a load on it, but usually ran okay going downhill.
With an ignition problem, you could get more erratic running, random
misfiring,backfires and thus a loss of power, or it could simply die
suddenly. Ignition problems can be load-related as well, if I'm not
mistaken.
The key is this: Both of the above conditions, in any and all of
their various forms, would cause the engine to lose revs, and thus
power. In some cases, the engine might lose so many revs that it
would actually stop running. But if you are perceiving a 'loss of
power' while the engine suddenly revs HIGHER, then we're not talking
about a either of the above. We're talking about slippage at either
the clutch or the overdrive. Neither a fuel starvation problem nor
an ignition problem would ever cause an engine to suddenly gain rpm
while losing power.
Pay attention to the rpms next time you're out. If the rpms drop
when you 'lose power' then you're back to either fuel or ignition.
But if the rpms increase with the perceived loss of power, then
you're talking about slippage in the drivetrain somewhere. That is,
the engine is still running fine and producing power, but the
drivetrain is not putting that power to the rear wheels and so it
feels like the power is suddenly gone.
--
Pete Chadwell
1973 TR6
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