Diesel engine wearing during the start up
Diesel engine wearing during the start up
(OP)
Hello everybody:
For a medium speed Diesel engine, I would like to know if an equivalent exists between the wearing down that suffer at the time of the starting up and the wearing down that suffers in normal operation; i.e. one start up equals, let us say, 20 or 50 hours of operation.
Thanks in advance
For a medium speed Diesel engine, I would like to know if an equivalent exists between the wearing down that suffer at the time of the starting up and the wearing down that suffers in normal operation; i.e. one start up equals, let us say, 20 or 50 hours of operation.
Thanks in advance





RE: Diesel engine wearing during the start up
RE: Diesel engine wearing during the start up
Normally, the engines start/stop daily.
Before the start up, the engines are (among others) in these conditions: Pre lubrication ON during 15 minutes; lube oil temperature > 40ºC; Heavy Fuel Oil circulating at 120ºC; pre heating water (High Temperature Water) circulating at 70ºC.
RE: Diesel engine wearing during the start up
RE: Diesel engine wearing during the start up
RE: Diesel engine wearing during the start up
If not it will not help those areas which are generally the first to wear out.
Regards
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RE: Diesel engine wearing during the start up
WR.
RE: Diesel engine wearing during the start up
RE: Diesel engine wearing during the start up
The engines operate during four or five full days, then comes the shut down and they remain stopped for five or six hours. After this time, they start once again.
RE: Diesel engine wearing during the start up
RE: Diesel engine wearing during the start up
I replaced a non turbo diesel engine with a new crate long block. After 130,000 miles, I tore it down to inspect for wear. The main and rod bearings, cam bearings and roller rocker bearings looked new. The cylinder bores had a like new cross hatch pattern except for a bald spot (worn smooth) on the thrust side near the top of each cylinder where the rod angle pushes the piston to that side. The rocker arm pivets had signifcant wear (aluminum against steel). I junked it running at 400,000 miles because of suspension and body wear.
It's my opinion that startup wear is mostly mith. Religious attention to oil changes and cooling system maint. is the best way to get the longest service life. I use straight weight 30 or 40 seven months out of the year. and multi 15 - 40 for the few cold months. The benfit of straight weight is that it is all oil without viscosity improvers taking up volume. I mostly buy worn out and abused vehicles but still get additional long use with minor roblems. I live in coastal NC where heat is generally more of a problem than cold.
RE: Diesel engine wearing during the start up
RE: Diesel engine wearing during the start up
Experience would indicate to me the taxi engine has about 3 times the life.
Regards
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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Diesel engine wearing during the start up
RE: Diesel engine wearing during the start up
For one every taxi i have seen is on LPG, so no fuel to wash the cylinder walls down.
I did some work on one once, It had a Genuine 980,000 Km,
lpg, V8. Heads done up once, Bottom end never touched! it was never going to get a million as a taxi tho, its 7 year limit was due.
All engines are designed to operate at a certain temperature, above or below too far and wear occours more rapidly.
Ken
RE: Diesel engine wearing during the start up
Huh? All of the engine technical specs I've seen have specified an environmental operating range of "-35F to +140F" (or so) - not "70F-90F and then they can cross their fingers."
For one every taxi i have seen is on LPG, so no fuel to wash the cylinder walls down.
Never seen an LPG taxi yet. My dad's cab was a regular ol' crown vic. Where were those LPG taxis?
RE: Diesel engine wearing during the start up
I expect taxi engines last longer for a number of reasons.
1) Minimal number of cold starts where internal clearances are far from optimal.
2) Minimal number of starts where many parts are not lubricated for a few seconds of running.
3) Use of LPG which does not wash down bores.
4) Engine oil regularly reaches temperatures which drive of corrosive volatiles.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Diesel engine wearing during the start up
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Diesel engine wearing during the start up
Yes, DownUnder i would estimate 99% or more of taxis are LPG fueled. Another reason, may be a wild thought tho, is the majority of taxis run in large cities, where dust is very uncommon, unlike rural areas where airborne dust is common.
Air filter maintanence and replacement is certainly much more critical in dusty conditions.
Ken
RE: Diesel engine wearing during the start up
RE: Diesel engine wearing during the start up
then again this question is going the way of the "combustion chamber pressures" thread.
We need to differentiate between the different types of diesel I think.
That said I'd bet that the "myth" of cold starts killing motors is more "fact" than myth.
Nick
I love materials science!