8V92 STARTING

[Woody]

Is there a 12V portion of this engine.

Went to the storage garage to give her the weekly run, turned on the 24V (but not the 12) and almost ground the batteries down with no start up.

Turned on the 12V and she fired right up.

Whats the connection?

[Jon Wehrenberg]

Woody,

The 12 volt is for the DDEC. It gets the power for the brains that control the engine from the 12 volt.

[JIM CHALOUPKA]

Woody, something good may have come from your experience with the 24V, 12V issue.
Awhile back there were several posts on worn cam lobes and followers and talk about pre-lubing.
One idea was that someone said to crank the engine over several times but without starting it to get the proverbial juices flowing. The suggested idea did not work as the engine starts immediately, as everyone knows, but ah ha you have come up with the answer for those guys that want to pre -lube!

TURN OFF THE 12V and crank away!!!!!!!!! :eek:

JIM :)

[Jon Wehrenberg]

So what you are suggesting Jim is that cranking but not starting doesn't eat as much metal as starting?

The idea behind a pre-lube is to replace oil which has drained from bearing surfaces on the crank and cam and other areas lubed via oil pressure as opposed to splash lubing.

[Coloradobus]

Woody, Your dilemma got me thinking. So, went out after dinner to start the bus..........dead. From the manual, states there is a jumper box to connect jumper cables battery charger to it, but nothing appears in the rear side compartment that looks like the diagrams in the manuals. Anyone have an idea/ JON? where to jump the bus from. Turned on the 2 breakers, and turned the key, made sure the "rear start' was on "Front" and nothing when twisting the key. No beepers, guages unmoving. From our Beaver Manual, it states there is a chassis battery charger. Apparently, its not there, inoperable, or faulty. Hmmmm. It has always started, but this time the coach has sat for 2 1/2 months. Our previous coach, I KNEW I needed to run every 3 weeks, but with an 8V-92, I thought we would not have this trouble.

[gmcbuffalo]

Jim and Chris
Beaver's design is that the inverter charger is wired to charge the chassis batteries while charging the house batteries. Do you have any switches off in the house battery compartment?
GregM

[JIM CHALOUPKA]

So what you are suggesting Jim is that cranking but not starting doesn't eat as much metal as starting?

The idea behind a pre-lube is to replace oil which has drained from bearing surfaces on the crank and cam and other areas lubed via oil pressure as opposed to splash lubing.

Not suggesting that at all, just voicing how to go about it if you think that is the case. Some did. I don't.

JIM

[dale farley]

Considering Jim's and Jon's comments, it does make you wonder how there is any benefit in our generators turning over 1-2 revolutions each time before they are allowed to start. Maybe they have a a special technology that instantly pumps enough oil to lube the bearings in only those 1 or 2 revolutions?

[Jon Wehrenberg]

I am far from an expert on engine wear, but in aviation it seems the engines that are used often, such as in a daily training environment almost always reach or exceed the recommended time for overhauls.

The engines that sit for long periods appear to be the engines that have a premature failure.

I read somewhere that the oil that provides the lubrication between surfaces eventually drains from between those surfaces thus allowing metal to metal contact and greater wear. That makes sense to me so if a motor is going to sit for long periods between uses it would seem some form of pre-lubrication would restore the lubricating oil to those surfaces such as between the bearings and the crank and cam and anywhere else pressure lubrication reaches.

But nobody has ever quantified how much wear actually takes place so that we can get an indication of if our engines for example will only go 500,000 miles instead of 1,000,000 or if the generators will only go 15,000 hours instead of 30,000 hours. Before I add pre-lubrication to the list of things I have to lay awake thinking about I guess I would like to see data that compels me to add it to my list of worries. Since our engines seem to have positive displacement oil pumps it is likely oil is hitting the bearings within seconds of the start of rotation so it is probably OK to accept so wear given that it is likely to be a miniscule amount.

[Woody]

A wise old Detroit Diesel mechanic at their Lodi NJ shop told me that this engine (8V92) especially must be started every week and run hard at least once a month or-------

[JIM KELLER]

Jon, So after starting your engine how long do you wait before hitting High Idle ? Do you wait longer when the engine is cold vs hot or do you go right into High Idle.

[Jon Wehrenberg]

Good question and I don't have a good answer.

Usually I start it and wait about 30 seconds or so before going to fast idle. Right after starting I am scanning the instruments to make sure they are all coming alive and are in the proper range. Then I go to fast idle.

Keep in mind however the bus rarely sees cold temperatures so it is very rare the engine is cold soaked. If it is cold out, the Webasto has been used and the engine is warm.

I have heard coaches start and immediately go to fast idle, and I am presuming the owners are just leaving the fast idle switch "on". I don't think that is good. I have had planes a lot longer than I have had the buses, and when starting the planes it is always my practice to start the engine and allow it to run at the lowest practical idle speed until I am sure oil has fully circulated, usually at least a minute or more, and to never exceed 1000 RPM until the cylinder head and oil temps are in the green.

We don't have a set of gauges in our buses with limits or gauge markings to denote normal range, but I like to see the coach temp gauges move off the peg before I get up to highway speeds. Fortunately most of the time, whether moving from home or from a campground I can idle slowly for some distance before getting above 1200 or 1300 RPM.

[rfoster]

I have recently been diagnosed with CRS, but I do recall that question was asked at United Engines Facility, OKC were the food was real good. I just don't remember the exact answer but I think it was wait two minutes before fast idle.

I must confess that I do not always follow those recommendations but I do try to wait at least one minute from a cold start.

Maybe someone who has not been infected yet can fill in the correct answer.

[truk4u]

I think starting an 8V or a series 60 once a week just to run it without getting it hot and up to temperature would be the worst thing you could do. When I have done it, I put them on high idle and let it run until normal temps are reached. United Engine said you could run it all day at high idle without any adverse effects.

[dale farley]

I usually do very similar to what Jon says he does. I start it and look at the gages a few seconds and then go to high idle. If I am starting cold, I make sure I wait a little longer. I am reasonably sure the manual says wait one minute before going to high idle. The main thing is that the oil has had time to reach all surfaces.

[James]

My operators manual states:

"After starting, run the engine at
slow idle for two minutes to allow lubricating oil
to reach the turbocharger. Then run the engine
at fast idle. Let oil pressure reach normal
operating range before driving."

Of course that is for the 2002 Series 60 and may not apply to other engines.

[Will Garner]

Wait a minute. What was Woody's question? I think it had something to do with starting an engine not with prelube procedures (are there really any?). Didn't he have some dead batteries?

Woody, I had a similar problem three years ago. The new batteries that came with the coach, yes they were only three months old, turned up dead one morning when Carole and I were going to exercise - the coach that is. It was a pleasant day so we sat outside the bus barn and watched as three Coach-Net service outfits came and went. "What, 24V,system, that is not what Coach Net said. We don't have anyway to jump start that engine." Well the fourth guy was determined to get the coach started, and get paid by Coach Net, so we removed the cables and found one of the batteries totally dead. Took it to Advance Auto where it was load tested and failed. So we went back with four new chassis batteries, replaced the cables, and off we went. That is we closed the bay doors and went home - too late to go crusing. Shortly after that experience I added a Guest #2611 battery tender so I would not have that experience again. So far so good. I'm looking at putting one on my house batteries to keep them charged also. You see, I don't have a 50 amp outlet in the bus barn (its not mine) and even if I did that would do absolutely nothing for the chassis batteries. It would only cover the house batteries on my coach.

Trukman has a wiring schematic to do the installation. It is really easy, so take your time and enjoy getting to know your 8V92 a little better.

Now as for the fast idle thread drift, I watch the oil pressure gauge and don't go to fast idle until there is 50-60 psi cold pressure. I have built many gas engines over the years and if you don't go to fast idle on an 8V92 you will see the oil pressure drop like a rock to about 10 psi. I'm told that is normal for this engine. On the engines I built, using speciality after market oil pumps, 50-60 psi was normal for a hot engine. Obviously 8V92 diesels are really different beasts from high performance gasoline powered engines.

[jack14r]

I wonder if the series 60 takes a little time to lube the rocker arms and if going to high idle too soon could create a problem in this area?

[rahangman]

As a newbie, I asked a couple of Drivers of tour buses, they seemed to think it to be a good idea to let my 8V idle normal for a couple minutes at least to allow belts,lube to "stretch" just like I should before working out! Just a thought

[Ray Davis]

I don't remember exactly where I heard this, but the word was that most busses which have had crankshaft damage was due to going to high idle too quickly. 2-3 minutes is the time I use.