Alan B
|
| posted on 14/12/13 at 11:54 PM |
|
|
Engine noise puzzle
Guys,
I'm sure you'll have answers for me...here is my puzzle..
Yesterday looked at a minivan (chevy venture if that helps) and before starting it up I went the rear and observed no exhaust fumes or steam upon
starting up...and the engine was nice and quiet.
So, did the deal and bought it.
This evening we went to collect it (I'd gone to the dealers at lunchtime to park it outside their premises for collection later) this time upon
starting it was smoky or steamy (couldn't tell which) and the engine was distinctly "tappity" sounding.
Any clues to explain the differing start up behaviour? If you didn't know any better you'd think it was different vehicles.
Alan
|
|
|
|
|
bill132hotrod
|
| posted on 15/12/13 at 12:22 AM |
|
|
Strange noises
On your first visit they had previously started the vehicle prior to you inspection so engine was already warmed up so hiding any problems when
starting from cold, tappety sound was most likely hydralic tappets rattling due to lack of oil changes in the past. These sometimes go quiet when
engine reaches normal running temperature.
PERSEVERANCE is the word of the week. Stick with it the results are SWEET.
|
|
|
chrism
|
| posted on 15/12/13 at 12:43 AM |
|
|
As the last guy said engine warmed up prior to last starting, the smoke/steam could just be moisture in the exhuast as observed on any cold
day/morning from queing cars in traffic.
----------------------------
A little hard work never killed anyone, but why take the risk!
-----------------------------
|
|
|
Alan B
|
| posted on 15/12/13 at 12:55 AM |
|
|
Thanks guys...good input...
Trouble is we arrived unanounced so I don't think they'd warmed it up first.....although it could have been warm already i guess..
Thanks,
Alan
|
|
|
jollygreengiant
|
| posted on 15/12/13 at 12:43 PM |
|
|
When looking at ANY car I always have a look under the 'hood' and if clean will examine the back of the engine bay by
'leaning' on the engine.
If engine 'to' clean why. has it been steam cleaned and why.
Leaning on the engine tells me if engine hot or 'stone cold'. If the slightest bit warm walk away.
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
|
|
|
liam.mccaffrey
|
| posted on 15/12/13 at 01:47 PM |
|
|
Not helpful but I had a chevy venture 
Build Blog
Build Photo Album
|
|
|
02GF74
|
| posted on 15/12/13 at 02:36 PM |
|
|
quote:
Originally posted by Alan B
Thanks guys...good input...
Trouble is we arrived unanounced so I don't think they'd warmed it up first.....although it could have been warm already i guess..
Thanks,
Alan
temp gauge would have shwon that - 2nd rule of car buying, always view with a cold engine.
.... and it you are curious what the 1st rules is, then never view a car when it is raining or has rained.
|
|
|
Slimy38
|
| posted on 15/12/13 at 02:41 PM |
|
|
quote:
Originally posted by 02GF74
temp gauge would have shwon that - 2nd rule of car buying, always view with a cold engine.
Not necessarily. An engine will run better if only slightly warm, long before the gauge moves. Best way is to touch the engine.
For the same reason, when the seller offers to 'start it up', i always say no and to lift the bonnet. This has the added benefit of being
able to see if the seller is using the throttle to get it running, another sign that there could be issues.
|
|
|
britishtrident
|
| posted on 15/12/13 at 03:05 PM |
|
|
It is best to listen an engine from cold until the electric fan cuts in.
Noise at cold start is usually from one of three sources. Tappet noise, Piston Slap or more seriously the big end bearings.
big end bearing failure is rare these days but sticking hydraulic tappet and piston slap are more common.
Tappet noise that goes away when warm is rarely a serious issue with hydraulic tappets it usually is down to the wrong grade and type of oil or
gummed up tappets can be fixed with a change of oil to the correct grade and type of oil (these days usually 5w/30 fully synthetic) and some
Wynnes Hydraulic Lifter Additive.
Hydraulic tappets give much less trouble if only fully synthetic oil is used as it doesn't form gums or varnishes and actually dissolves
existing deposits, and oils that are thinner at the cold end get through to the tappets more quickly after a cold start and don't pump up the
tappets.
If left without being started for a a few weeks the old Rolls-Royce V8 engine used to take a good half hour running before the hydraulic tappets
refilled and quitened down.
Piston slap was a problem in the early days of motoring that came back as designers tried to be clever and reduce the friction in engines. GM
engines in European Opel and Vauxhall cars suffered from it more than most, it generally goes away as the engine reaches full running temperature. It
generally isn't a serious issue.
Toyota have also had problems with piston slap on engine with over 70,000 miles on the clock, they maintain it is a maintenance issue caused by using
the wrong spec oils.
All cars produce steam from the exhaust every 1 gallon of petrol burn't produces 40 gallons of water from the exhaust but you can't
see steam. What you are seeing is condensate from the steam which is caused by a combination of weather conditions and the exhaust gas temperature,
if the gases coming out the exhaust falls below the ambient dew point the water vapour will condense out the exhaust gases and you will see clouds
of what you call steam.
The only time this requires action is if it is accompanied by coolant loss or the engine either over heating or over cooling.
[Edited on 15/12/13 by britishtrident]
[Edited on 15/12/13 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
Alan B
|
| posted on 15/12/13 at 04:16 PM |
|
|
Really good advice guys thanks......I should have asked first though...
Looks like it's going to be OK...
Cheers,
Alan
|
|
|
