Author Topic: What happened?  (Read 725 times)

Offline BruceK

What happened?
« on: September 18, 2017, 05:28:25 PM »
I was driving my Mini in the highway yesterday going about 65 mph in fairly heavy traffic when all of a sudden the car in me slammed on its brakes (later saw it was a stalled car up ahead coasting to the roadside)   So full panic stop for me too down to zero with all the resulting adrenaline impact.  My car stopped great - at least 20 feet from the car in front.    Naturally, my eyes went right to the rearview mirror to make sure the car behind me was going to stop too.   

Immediately traffic started moving again and I started accelerating to keep up.  As I was regaining speed I looked out the rear view mirror and saw my car spit out a fairly large plume of white smoke.  My engine started making a knocking or tapping noise -- I thought maybe it dropped a valve or something.   I needed to keep moving with traffic and as I got into 2nd gear the noise and smoke stopped and the engine ran fine.  I glanced over at the oil pressure and it was reading 60 PSI or so as I was gaining speed.  Elapsed time - from full panic stop to accelerating back up through the gears - was perhaps five seconds or so. 

My guess is the full panic stop caused oil to move away from the oil pickup and the engine was starved of oil for a few seconds?  Does that seem plausible? When I got home I found the oil level was at the bottom of the range and I added 1/2 qt.

I just pulled the spark plugs to check compression and all cylinders read 175 PSI except for number 1 which reads 170.  So all seems good there.  The plugs seem to be fine and indicate nothing wrong with the fuel mixture.

So, what do you think?
« Last Edit: September 18, 2017, 05:31:09 PM by BruceK »
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville

Offline 94touring

Re: What happened?
« Reply #1 on: September 18, 2017, 05:38:22 PM »
First I've heard of that.  At first I expected to read you got rear ended and would be bringing the car back.   Maybe fuel got sloshed around and ran lean momentarily?

Offline MiniDave

Re: What happened?
« Reply #2 on: September 18, 2017, 06:56:28 PM »
Or fuel sloshed into the intake and it got rich on one cylinder for a few seconds?

I doubt it starved for oil, and that wouldn't cause a puff of smoke either.....

Or panic stop forced brake fluid into the booster where it got drawn into the intake and burned - only if you have  a brake booster of course. Brake fluid will burn white.....
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline BruceK

Re: What happened?
« Reply #3 on: September 18, 2017, 07:13:03 PM »
So, running lean or burning brake fluid?  Hmmm.  Sounds plausible.   What could account for the loud tap-tap-tap-tap noise that went away after 5 seconds or so?

I just want to make sure she's healthy for the trip to Austin for the British Car show this weekend (assuming it doesn't get rained out)   She ran great for the 20 minute drive home after the panic stop incident, so I'm probably just being a little paranoid.
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville

Offline MiniDave

Re: What happened?
« Reply #4 on: September 18, 2017, 07:45:50 PM »
Does Emma have a brake booster?
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: What happened?
« Reply #5 on: September 18, 2017, 07:59:21 PM »
Brake booster theory makes sense too.

Offline BruceK

Re: What happened?
« Reply #6 on: September 18, 2017, 10:29:17 PM »
Yes there's a big late model brake booster that mounts to the firewall.   I checked the brake fluid level and it's fine -  so unless I lost a very small amount of brake fluid that didn't happen. 
« Last Edit: September 18, 2017, 10:31:07 PM by BruceK »
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville

Offline MPlayle

Re: What happened?
« Reply #7 on: September 18, 2017, 11:07:01 PM »
Carb or fuel injected?  If carb, what are you using as dash-pot oil?  Could that have "sloshed" out and into the intake along with a surge of excess fuel from the hard braking?


Offline BruceK

Re: What happened?
« Reply #8 on: September 19, 2017, 12:25:15 AM »
HIF carb with Mobil 1 5W-30 oil in the dashpot (selected because I had it to hand).   Interesting theory, but all the smoke was out the tailpipe in one 2 second blast  i'm very familiar with the smell of oil on headers and I didn't smell a thing  from under the bonnet.   

By the way, the car accelerated normally no hesitation or stumbling.   The really weird part was the loud tap-tap-tap noise.  At that brief moment, I was convinced the engine was blown and I was heading toward the side of the road to pull over when the noise stopped and everything returned back to normal.
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville

Offline 94touring

Re: What happened?
« Reply #9 on: September 19, 2017, 07:19:37 AM »
Maybe a miniscule amount of water in the tank that found it's way to the pickup tube in the tank when it got sloshed around hard. 

Offline MiniDave

Re: What happened?
« Reply #10 on: September 20, 2017, 02:28:32 PM »
Very strange indeed, but as it "cured" itself, I don't think I'd worry about it any further.....
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline velopackrat

Re: What happened?
« Reply #11 on: September 20, 2017, 03:30:44 PM »
Bruce,
Regarding the tap tap tap, that would have me pretty freaked out too.  A sound as if the oil went away briefly?  Although not likely you could run the sump dry by sloshing oil.  Otherwise all Mini race motors would blow up after long straights followed by hard braking.  Slight exaggeration but you get my drift.  But what if the rockers went dry for a few moments?  Would the timing of the tap tap and the noise it made sound like that?
Can you remove your rocker cover without too much pain and take a look around?  Rockers using the stock washers and springs can be slid to the side without loosening anything (assuming they are not depressing a valve) so you can take a better look.  Check the rocker shaft and check the points of contact.  Might need a mirror, I can't remember.  You can also rotate the push rods around to insure they aren't bent.  Checking costs nothing.  Maybe a rocker gasket.
Chris 

Offline MiniDave

Re: What happened?
« Reply #12 on: September 20, 2017, 07:07:05 PM »
I think the sound was more likely a combustion event, much like pinging.....something it ingested and took a few strokes to work out again, if it were rockers it would probably still be doing it. Plus too and also, the rockers don't get (or need) near as much lubrication as say the rods and mains, so a quick loss of oil pressure would not be heard from the rockers.

I think I wouldn't worry about it unless it did it again. If it does I would try to decide if it followed the RPM or half RPM - that would decide if it's the upper or lower end that's doing it.

I also doubt Dan's water in the tank theory, by the time the pump moved it all the way from the tank to the carb and into the cylinder, quite a bit of time would have to go by, it wouldn't be immediate like he describes and it wouldn't be just the one cylinder as I think Bruce is describing.....the puff of white smoke takes me back to brake fluid, it wouldn't take a whole lot to do that and make one cylinder miss or make noise, and the vacuum port is right on top of the intake, directly above cylinder #3.......
« Last Edit: September 20, 2017, 07:10:31 PM by MiniDave »
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline BruceK

Re: What happened?
« Reply #13 on: September 25, 2017, 12:44:00 PM »
So 500 mostly highway miles later after a weekend trip and whatever happened last weekend, apparently didn't matter at all.

Chalk it up to a car burp or fart. 
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville

Offline Minty

Re: What happened?
« Reply #14 on: November 26, 2017, 09:30:44 PM »
any updates on this?

Offline John Gervais

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Re: What happened?
« Reply #15 on: November 26, 2017, 11:05:26 PM »
I agree with Dave - sounds like a combustion event and my thought is a bit of lean-burn misfire or detonation. 

I've been battling this myself, when I cruise for a bit and stop at a traffic light at the end of an exit ramp for example.  In my case, I can 'see it' go wicked lean by watching the wide-band A/F display (sometimes off scale!   :-\).

Nobody I know can 'splain to me 'why' this is happening - brand new HIF38, mixture's good, float's correct, fuel pressure's 3 psi, no vacuum leaks, dizzy freshly reworked at Aldon. 

If I'm lucky, Santa will deliver a rebuild kit for the HS2 twins...
« Last Edit: November 27, 2017, 12:34:21 AM by John Gervais »
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Offline BruceK

Re: What happened?
« Reply #16 on: November 27, 2017, 08:04:06 AM »
any updates on this?

Sorry, I missed seeing your question.   

I've driven probably 800 miles since then and the problem has never returned.   
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville

Offline MPlayle

Re: What happened?
« Reply #17 on: November 27, 2017, 09:28:25 AM »
John,

A hypothesis on your "lean out" condition:
- Dashpot oil viscosity slightly light
- Extended cruising at speed permits under bonnet temps to "thin" the oil a bit more
- The rapid drop from cruise combined with the thinned oil lets the dashpot spring "slam" the piston down, making the needle rapidly cut off fuel flow versus the throttle vacuum
- Resulting in momentary "extremely lean" condition

It sounds plausible to me, but no expert here.  Just a possible theory that came to mind.


Offline 94touring

Re: What happened?
« Reply #18 on: November 27, 2017, 10:02:28 AM »
Always the possibility of gunk in the fuel system. A bit of debri here or there can clog things momentarily.  My old tank kept clogging fuel filters with rust flakes.  What a great day it was when I swapped tanks.

Offline Bahowe1

Re: What happened?
« Reply #19 on: November 27, 2017, 04:10:26 PM »
I've got a theory. White smoke, I think coolant. What if... a really hard stop, third engine steady (or something else) creates a force that ever so slightly opens up head gasket to allow a smite of coolant in a cylinder? The coolant is the pinging.
Just a theory, crazy as everything else.

Offline MiniDave

Re: What happened?
« Reply #20 on: November 27, 2017, 04:39:08 PM »
A sudden ingestion of liquid of any type in the cylinder while it's running will cause a tap or knocking noise, as it gets burned off, it goes away. I'm sticking with my earlier recommendation - don't worry about it!   ;D
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline John Gervais

  • A Really Swell Guy
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Re: What happened?
« Reply #21 on: November 27, 2017, 10:00:26 PM »
John,

A hypothesis on your "lean out" condition:
- Dashpot oil viscosity slightly light
- Extended cruising at speed permits under bonnet temps to "thin" the oil a bit more
- The rapid drop from cruise combined with the thinned oil lets the dashpot spring "slam" the piston down, making the needle rapidly cut off fuel flow versus the throttle vacuum
- Resulting in momentary "extremely lean" condition

It sounds plausible to me, but no expert here.  Just a possible theory that came to mind.

Not too far from what I'd thought too - I've experimented with 5W, 10W, 15W, 20W & genuine SU damper oil, red spring, red spring with a bit removed to slightly increase pressure from 4.5 to 5oz, a yellow spring - and then I read a bit more about SU dampers.  KC gave me a mono-metalic jet holder, his last one, so fuel temperature shouldn't be a factor. 

I'm tempted to start looking at the float valve.

Have you seen these?  The first article, MIM211 has some really good info -
- Pave the Bay -