Wednesday, October 18, 2017

Riding a Zombie

Can a Vespa rise from the dead?

Is it possible for a blown head gasket, something akin to a brain aneurysm, to heal spontaneously?

If not, was the gasket in fact blown?

And if not, whence the coolant leak?

So many questions. For the time being no satisfactory answer.

Here are the facts as I know them. I need your insight.

After a long day’s ride from State College to Niagara falls, some 370 kilometers, a coolant leak in the engine compartment brought the day’s ride to an abrupt end.

It was impossible to see the source of the leak. The coolant was running down onto the center stand pivot or axle and dripping from there. You can see this symptom in the video I posted as episode 22 of the vlog.

Other symptoms: when I opened the saddle to refuel, steam was rising from the engine compartment. When I removed the underseat bucket to reveal the engine, there was coolant everywhere, as if there was a spraying coolant leak. The underside of the seat compartment bucket was wet. When I started the bike with the bucket out, the coolant was dripping from the stand below the motor, but there was no evidence of a leak seen from above the engine.

That’s all I’ve got.

Last week I needed to get my bike down from its P1 parking spot to a temporary spot on P3 because the P1 level was being pressure washed.

I refilled the cooling system with tap water, up to the lower fill mark on the reservoir. I fully expected to see the water begin dripping down the stand. But there was no leak. I started the motor. Still no leak. I left the motor running until the bike reached normal operating temperature. Still no leak.

I rode down to P3. Still no leak.

Two days later I checked on the bike before riding back up to P1. Yup, still dry.

I discussed the situation with Ed Thomas. Ed thought that perhaps the water was leaking into the oil pan via the blown gasket rather than leaking to the outside. He suggested checking the coolant level in the reservoir, and checking the oil level. If both were at their normal levels, it would be reasonable to conclude that the coolant wasn’t leaking into the oil. I checked and the levels were normal.

Today I decided I would hop on the Vespa to run a few errands and eventually make my way over to Ed’s workshop, to talk, well... talk shop, and zombie Vespas. You guessed it, still no evidence of any leak. That, and I kept an eagle-eye on the instrument panel: the engine temperature remained normal the whole way. The check engine light lit up a couple of times, but reset itself with an engine restart. That happened three times on the way to Ed’s, each time shortly after one of my little errand stops. It never happened on the way home.

Ed’s as stumped as I am.

The only other thing I can think of, is that close to the Pennsylvania New York border, I refueled at a tiny country gas station, and I realized that the helpful attendant handed me a nozzle switched to regular gasoline with ethanol. I only realized it had happened further down the road when the engine started stumbling slightly. Three tanks of 91 octane fuel later, the performance symptoms disappeared. I don’t think that’s relevant. I just mention it because it’s the only other engine-related issue that occured on the trip.

So there you have it. The Vespa seems for all the world to be running like a top. Or at least running as well as it did when I set out for the wilds of Pennsylvania.

I know many of my readers have what I’ll call mechanical literacy. What is your take on this little Italian mystery?

Is there any chance that the coolant leak might have come from the coolant bleed valve at the top of the engine?

Can a blown gasket heal itself?

Should I overhaul the engine on the assumption that there is a defective gasket?

What would you do?

Like I said, I am stumped.

Thanks for reading.

PS: I also posted this mystery to the ModernVespa forum: here’s a link.

PPS:

In this shot taken from the Episode 22 video, filmed within 15 to 20 minutes of the discovery of the leak:
  • The circle is the thermostat housing and the nubby thing in the circle at the twelve o'clock position is the coolant bleed valve.
  • The arrows point to the areas that are wet as a result of the leak. 
  • Remember that the pet carrier / underseat container was in place when the leak was leaking. It seems consistent with a leak from the thermostat that the wet areas are aft of the thermostat. 
  • The areas forward from the thermostat are dry.
  • Whatever that evidence points to, it is not really consistent with a head gasket leak, or so it seems to me.


Another MV'er (whom I believe to be another mechanically literate person) had this to say: "It is very rare to have an external coolant leak turn out to be a head gasket. It would usually go into the engine oil or out the exhaust."

Yet another MV commenter had this to say: "Hmm. Not clear whether you mean the gasket at the base of the cylinder (possible) or the one which seals the two halves of the crankcase (unlikely). You don't develop anywhere near as much pressure in the crankcase and spraying coolant all over does not seem likely to me. You would lose engine oil if anything. I think the thermostat/bleed valve area sounds far more likely as you suggest. Probably time for a trip back to Vespa Toronto West for reconsideration."

16 comments:

  1. Hi David,
    Just a thought mate,
    I had this happen once on my GTS300 and I swapped out the thermostat and it never happened again, my thoughts were perhaps it jammed shut and water in the coolant chambers around the block boiled over due to not being able to travel around the constant normal operation loop.
    Does that make sense??
    Regards

    Len



    Sent from my iPhone

    ReplyDelete
    Replies
    1. Len that does indeed make sense.

      Amazing, just the kind of insight I was praying for.

      Thank you so much!

      Delete
  2. I’m with Len...stuck thermostat. There’s certainly an overflow hose from the radiator and depending on where it exits, a bit of water vapor on hot components could look much worse than it is. Stopping, cooling down, thermostats can easily open up again.

    ReplyDelete
    Replies
    1. Doug, thank you, thank you, thank you.

      So far the thermostat as the culprit is three for three (one other person chimed in on my ModernVespa.com post which I’ll link in this post).

      A ~CAD$15.00 problem is way better than the original ~CAD$1,500.00 diagnosis.

      Delete
  3. Not that you need my vote, but make it unanimous - thermostat.

    ReplyDelete
    Replies
    1. Thanks David, and yes, I do need your vote, and I have to say, it carries a lot of weight. Thank you very much.

      Delete
  4. No problem David,
    Happy to help.
    Certainly wouldn’t have been a fuel issue, I really can’t see anything but a jammed shut thermostat causing that or just maybe the thermostat sensor didn’t do its job?
    It may never happen again but for the sake the low costs to swap out it’s worth doing as it could catch you out on a long run when least expected.
    To absolutely be 100% sure you could do both the sensor and thermostat.

    When changing the sensor there is a bleed nipple on the block which you’ll need to do afterwards regarding the sensor.

    Also worth unclipping the multi-plug that goes onto the sensor and making sure it’s connected right.
    One other thing there’s a black ECU grounding/earth cable that bolts onto the engine block, if this as come loose at all then that could have caused a problem with the sensor not doing its job and throw up the engine warning light.
    Feel like I’m waffling now😃 just scratching my head trying to cover every avenue.

    Is the fan kicking in/out at full operating temperature as per normal or does it do it early?

    Regards
    LEN
    WWW.REGLAZE-IT.CO.UK

    ReplyDelete
  5. David,
    One more thing from watching the Vlog I have to say the wobble on a GTS is quite normal a lot of GTS rides will mention this.
    Regards
    LEN

    ReplyDelete
    Replies
    1. Thanks for the additional suggestions Len

      As for the wobbbbbble, I know, I know. Mine made the dealer feel unsafe so mine might be quite pronounced. That’s an issue I might tackle myself.

      When I rode Ken Wilson’s 2015 GTS there was absolutely no wobble. I think Piaggio finally tweaked the front end geometry. After all, 1940’s aircraft landing gear was an inspired choice for the Vespa’s front end in the late 40’s, but probably not as ideal as a good old-fashioned fork.

      Delete
    2. Hi David, while my orange one (2015 model) had no wobble at all, Roland's Vespa (2008 model) was terrible. He didn't mind, but now that I am regularly commuting on Bella, and felt uncomfortable with the wobble I opted to put heavier (custom made) end pieces on the handlebar, and switched to Heidenau tires. It's almost completely gone now.

      Delete
    3. Thanks for that Sonja. I think that there is some inherent wobble. I know people love Heidenau tires. I don’t think they are available here. I have the heavier bar end weights that come with the topcase. Are you saying there are even heavier weights available?

      I also think my steering column needs some adjustment.

      Delete
    4. BMW K75 wobble: When I first stuck the kitchen on the back of the bike there was some minor wobble. More weight, more wobble. The next year on new tires the wobble disappeared. Had a minor shake on Sat, but I think my front tire is a couple lbs low. Does weight on the front rack make a difference?

      Delete
    5. Distributing weight more towards to the front/more evenly helps. A front rack didn't solve my wobble, but it made it less pronounced.

      Eventually I replaced the front fork bearings, and while it improved the handling the bike still wobbles. It only happens when decelerating through lower speeds, I've just come to accept it as a feature.

      Glad to hear the bike is back from the dead-ish?! I keep hearing how difficult it is to actually kill a GTS. Hope the thermostat replacement works out!

      Delete
    6. Thanks Steph! I am know thinking that the wobble is just not such a big deal (I didn't think it was before the dealer reacted so negatively to my wobble).

      I saw that you replaced your bearings on your own, but in a proper shop with a lift. I wonder if I could tackle that in an underground parking spot?

      I was also debating a front rack for better weight distribution. As it is I tour with 5 liters of fuel on a floor rack, but it doesn't seem to affect the wobble.

      Delete
  6. So, does this mean that the Vespa is back on the road on a regular basis?

    ReplyDelete
    Replies
    1. Yes indeed it does Richard.

      With a little luck I’ll pay a visit to the dealer tomorrow and pick up a new thermostat and a seal for the water pump. Then some distilled water. I plan to flush the cooling system, change tge thermostat, inspect the thermostat housing, and if all is well, replenish the coolant.

      It will be interesting to see what that yields. I always found the bike ran on the hot side. It may be that the thermostat was always dodgy.

      If it still runs hot, I’ll have a look at the temperature sensor as well.

      One thing is certain, there is no blown head gasket.


      That is a huge relief.

      Delete

The copyright in all text and photographs, except as noted, belongs to David Masse.