Good Morning having troubles with my 8v92T Engine starts and runs smooth until you put your foot into it after 1500 RPM ,,, feels like its starving for Fuel or Air .
Ive changed the Air Filter and changed the fuel filters ,,, also ive primed the system by using a hand pump but cant seem to keep the engine running .
Any thoughts on this ..... im thinking the fuel pump is weak ... witch would explain it bagging out after 1500 RPM when it was running prior to me changing the filters .
Is the fuel pump on a 871 the same as a 892 .... they look the same .
Dave
Install a gauge in the top of the secondary filter and check the pressure you should have 65 lbs it may be the yoke rounded off slipping,I replace those pumps with the DDEC high volume pump a better pump IMO if it runs at 1500 rpm I doubt it is the fuel pump fwiw
You haven't indicated what vehicle this engine is installed in,,if a bus, most are 40- 50 years old so pressure check the fuel line from the tank, most are metal and corroding from inside out.. >>>Dan
LuvrBus witch yoke are you refering to
Thanks Dave
Hi Claim Jumper
The 8V92T is a low klm instaled in a 92 MCI 102c
Dave,there is a yoke that drives the fuel pump off the blower remove the pump and you will see the yoke they are bad about the square shaft on the pump rounding the hole in the yoke I always replace the yoke when replacing the pump fwiw
Could be a baffle in the muffler blocking the flow. Might take off the muffler for a run if you can't find anything else out. Besides-it just sounds cool with a straight pipe. Good Luck, TomC
Any chance a fuel line is collapsing? Are the fuel filters full after you drive it?
When you "floor" it, does it smoke? White or black?
Is the turbo plumbing leaking? Is there a whistling noise going down the road?
Might need a helper in the bedroom for that one. Get one with good hearing, most of us are half deaf.
Is the throttle cable stuck? Check to see if the fuel arm is moving through all of it's travel.
If none of these or the other suggestions you have received help, let us know.
There is a vast amount of knowledge on this board.
Was able to get the engine running again and stay running , i went threw the priming process a zillion times with no luck it would suck the filters dry and the engine would quit . I called the local fuel truck operator got him over and we filled the fuel tank to the rim it took 176 littres then went threw the process again ... filled the primary and secondary filters. Then using a bulb primer with hose into the top of the fuel filter bracket i pumped best part of a 5 gallon jerry can into the system then stuck the hose into a full 5 gallon jerry can .... then started the engine it sucked the 5 gallon jerry can close to the bottom i shut the engine down replaced the bleeder screw where i had the the hose contected ... started it up its running again .
The problem of it bagging out after 1500 RPM still there ..... but adleast i know its not the filters ill check out the yoke on the fuel pump tommorow
Thank you every one all keep you posted .
Dave
Akroyaleagle the filters are full after taking it for a good run .... the engine runs nice and clean as it always has no smoke ... ill check the throtle tommorow and look for a collapsed fuel line
Tomc all also check the exhaust
Thanks every one all keep you posted
176L = 46 gal of fuel. Low fuel wasn't the problem.
If it is sucking the filters dry, it probabably is not the fuel pump.
To check it would require the engine to be over 1500 RPM, if that's where the problem begins.
It would still pump the bucket dry if below 1500 RPM.
Everything I have seen here suggests to me there is a problem in the fuel supply line.
If you hand pumped 5 gallons of fuel through the filters without the engine running,
The one way valve in the lines that keeps the fuel from draining back is faulty and
you are pumping it into the tank.
Maybe try replacing the fuel restrictor?
It could be his engine has fuel modulator or a throttle delay that is out of adjustment if the engine has either
ck hot side of turbo.. Exhaust manifold gasket. look at bottom especially loss of exhaust pressure = loss of boost=loss of power. Just a guess and it happen to me. Also I have found on the 98 I'm doing now the fuel supply line is dry rotted and was sucking a minute amount of air under high demand /also look for a rubbed place against a line or surface.. I replaced it from tank back. I would not have thought a braided coated line wound deteriorate in that short amount of time--was in a non heat area where problem occurred. Also while we are covering the non-usual on one engine I had a valve spring break and the engine fall off a couple hundred rpm. Since there are more than one the engine ran but preformed low. That was a hard find. Easy with valve cover off. One more low voltage to your DDEC anything under 11 volts. If you have multiple batteries the feed to the DDEC is normally fed off only one =If that one is weak= low ddec feed= That's all I got.
Ive tryed everything but the Colapsed exhaust ..... i notice the steel braided fuel line off the primary fuel filter has been rubbing on the barn door where the licence plate indention is .... it just might be getting air all get a new line made up at Wajax in Yellowknife Monday in the mean time ill pull the muffler off ... see if runs full power after 15000 RPM .... it is smooth as silk till hits 16000
Thanks
Dave
If the filters are dry it would seem plausible that air is being introduced someplace between your full fuel tank and the filters. Mine has hard lines between the tank the the primary filter - I would suppose that if you had the same you could have a small crack or an area that has been rubbed through. Maybe a loose fitting? Soft lines could be rubbed through as pointed out earlier. Good luck.
Seems put the fuel pickup line in a full 5 gal bucket would give a big clue ?
Dave M
The only time i was having problems with it sucking the filters dry was prior to having the fuel tank toped off , after i topped the tank off engine took the prime and started flawlesly runs perfect now untill it hits 1500 RPM , thats why i changed the filters it runs great untill it goes over 1500 RPM
Thanks
Dave
Is the fuel engine shutoff thingy hanging up and not leting it come back all the way,mine would do that and a had to pull it back by hand after a shut down
Quote from: Nineforever on March 16, 2014, 07:59:07 AM
see if runs full power after 15000 RPM .... it is smooth as silk till hits 16000
Thanks
Dave
Yup, I had the same problem when I tried using a Formula 1 racecar engine in my bus, but when I put the Detroit back in it was OK again.
Seriously though (!), as Luvrbus suggested, put a fuel pressure gauge in the spare port on the side of the secondary filter, then it will help you narrow down where fuel-related problems may be. I did this a while ago - well worth it. When you try to run the engine over 1500 RPM, is it under load (at what turbo boost pressure?) or at no load?
John
The fuel filter to the left is the primary filter correct ...... and the filter down under to your right is the secondary ... when you open the barn door correct or vise versa
Dave
Dave, look at the fuel lines. The supply line from the tank comes through the fire wall, then to the primary filter. From there, it goes to the fuel pump, then to the secondary filter, then to the heads. Then from the heads back to the fire wall and the fuel tank. The lines are under suction from the tank to the primary and to the pump, then under pressure from the pump onward.
JC
Ok then ill check that out
After looking closely at the muffler maybe good idea to change it does any one have an aftermarket part # for this rather then ordering it threw MCI
Go to the Donaldson site. There are numerous mufflers available. Just have to get one that fits with the correct fittings and flow characteristics.
I'm using a 5" inlet and outlet on the same end oval muffler that's about 20" long made for turbo engines. It puts out a nice tone with no back pressure. Good Luck, TomC
Tomc you were correct it was a colapsed exhaust muffler
Thanks every one for input
Nice to hear that it is a relatively cheap repair! Good Luck, TomC
I don't know if you got a new muffler yet, but sometimes you can cross from an MCI part number. I needed a new muffler for my Dina and MCI wanted over $1000. After a lot of work I found a cross for the MCI number, but it was listed as Universal Coach Parts instead of Dina or MCI. I paid less than $400. (Universal Coach Parts used to be the parts division for MCI.)
I really wanted to use a different muffler, but the way everything underneath is arranged I couldn't find a way to make another muffler fit.
I've got a brand new never installed muffler for an 8v-92 that I got from Prevost for sale cheap! Well lots cheaper than a new one!
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Big 5" muffler should be less than $200.00. Good Luck, TomC
Tom mine was $700 from Prevost and that was a few years ago!
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Seems the perfect time for a resonator, many have made the switch and would never go back to the OEM muffler. The increase in useable hp is surprising to most, of course most can detect a small increase in hp while a few could not detect a 200 hp inprovement, so for those, go ahead and purchase the OEM setup and enjoy.
Dave M
Quote from: wg4t50 on March 25, 2014, 03:20:46 AM
Seems the perfect time for a resonator, many have made the switch and would never go back to the OEM muffler. The increase in useable hp is surprising to most, of course most can detect a small increase in hp while a few could not detect a 200 hp inprovement, so for those, go ahead and purchase the OEM setup and enjoy.
Dave M
Dave, I am running the DD 60 series, was there a noticeable noise increase in changing to a resonator? My OEM muffler is very quiet which is nice and which came from Prevost. But if there is a HP advantage with a resonator I would really take a look at changing.
Once again-go to the Donaldson web site and look through the truck mufflers. They also have many tables as to the proper muffler for your engine. The 8V-92TA is at the top end of the 5" system, so the proper muffler with enough exhaust flow is critical. When you find the correct muffler, go order it from a big truck dealer. It will always be cheaper then from a bus dealer. Good Luck, TomC
The DD Engineering Bulletin # 39 dated Sept 1987 revision 2 states a 6 inch for a 8v92TA, 5 inch is for a 6v92TA,8v71n/a and the 8v71T fwiw
Boys would it be better on engine with straight exhaust and let her rip on A 8V92TA?
PS,
I like to be noticed! ;D
Boy howdy, wouldn't be cool to put 5" fish tails ( no muffler of course ;D) on and let er' Rip. ;)
The 8v92TA is really not all that loud without a muffler you can hear the turbo more tho, but the N/A 71 are very loud
Does any one have a part number for after market muffler for 8v92T its factory 5 inch looks the same as a 8v71 n but its diffrent inside back pressure is diffrent
I think you will find if that is the original muffler it will be a Nelson not a Donaldson so check out the Nelson then cross it over as a Nelson is a high $$$ muffler you won't buy one for 200 bucks like a Donaldson take your measurements and go to www.unitedmuffler.com (http://www.unitedmuffler.com) they will have one
When I bought my first truck with a 8V-92TA, it had a single 5" up exhaust. Course it only had 9A90 and rated at 435hp. Pushing a 500hp, I could see using 6" exhaust-but-6" really gets expensive. Good Luck, TomC
Nelson was the only one who still made my particular muffler. It was either pay $350 for a Nelson or over $1000 to MCI for something they probably bought from Nelson. Walker used to make the muffler also, but they discontinued it. The same muffler is also used on several Navistar trucks so I'm surprised so few make it. I used the Navistar part numbers too, but that didn't help.
Back in the 1960's with the turbocharged Corvairs, we found that the turbo reduced the need for a muffler by 90% so a resonator was all you really need behind a turbo.
e3
Some things DD done never made any sense to me like the 8v92TA has 2-1/2 exhaust manifolds they want a 6 in exhaust then the 8v71N/A has 3in exhaust manifolds they want a 5in exhaust the DD way but it works ::)
On a turbo engine you have smaller primary tubes (the manifolds up to the turbo) to keep the velocity of the exhaust gas high. After the turbo you want as low a restriction as possible hence the larger diameter. On a natural engine you just want low restriction everywhere, so you go big from the head. My 8V-71NA had 4" off the manifold but the turbo version was 3" up to the turbo.
Brian
Turbochargers are thermodynamic devices that operate on heat, not pressure or exhaust velocity. Less restriction everywhere is a good thing, but exhaust manifolds and "downpipes" to the turbo radiate off more or less heat depending on their size and metallurgy.
Cheers, John
My turbo conversion on my 8V-71-Don Fairchild installed a 12.7 liter Series 60 turbo since it has a dump valve and we adjusted it for 15psi max all on 5" through a Donaldson turbo muffler. The left manifold wraps around the front of the engine to the right side where the turbo is mounted. It takes a couple of minutes for the manifold to heat up on a pull before smoke disappears. Love the setup. Going from N65 to 7G75, went from 300hp and 800lb/ft torque to 375hp and 1125lb/ft torque. Good Luck, TomC
Tom is right on this one. For optimal low end or max low RPM torque we want the turbochargers to spool up quicker/sooner. This is done with short primaries. The exhaust port velocity needs to be as high as we can get it. Porting turbine housings, porting exhaust manifolds..
Your talking a resinator whats that acctualy ... is there a part number for my application
In car talk, we used to call a resonator a glass pack. Basically a short muffler that you can see right through it. It provides around 3-5dba of sound reduction compared to a big muffler that can be 10-20dba reduction. Good Luck, TomC
My experience has been the large reduction in harshness using the tesonator on A 8V-92.
Dave M
Would it hurt to run them straight? Had a Turbo charged small block Drag car in the late 70's and that thing hardly made a sound compared to the conventional motors with headers with no turbo.
My first setup 8V-92 was a straight exhaust from turbo, I liked it on the MC7 as I was way forward of the exhaust, however comments were made about the loudness, so has a Walker 5" resonator, with two 5" band clamps, it was on. Everyone agreed it was much more livable, as less harsh. Is still on the bus.
Dave M
Have had my 8v92t straight pipe for last couple years mexican border to the canadian border several times, never had anybody complain..bus run so much cooler and better don't care if they do complain,never see em again anyway.
Quote from: dukegrad98 on March 27, 2014, 01:56:28 PM
Turbochargers are thermodynamic devices that operate on heat, not pressure or exhaust velocity. Less restriction everywhere is a good thing, but exhaust manifolds and "downpipes" to the turbo radiate off more or less heat depending on their size and metallurgy.
Cheers, John
John you are getting gas and diesel turbos mixed up, here's a good article that explains the differences and why it is more of the gas/air volume on a diesel turbo that makes it work whereas on a gas turbo heat definitely plays a big role in it's efficiency.
http://www.wcengineering.com/articles/dieselturbo.html (http://www.wcengineering.com/articles/dieselturbo.html)
Quote from: digesterman on March 29, 2014, 12:13:50 PM
John you are getting gas and diesel turbos mixed up, here's a good article that explains the differences and why it is more of the gas/air volume on a diesel turbo that makes it work whereas on a gas turbo heat definitely plays a big role in it's efficiency.
http://www.wcengineering.com/articles/dieselturbo.html (http://www.wcengineering.com/articles/dieselturbo.html)
Thanks for the chuckle! ::)
Cheers, John
Quote from: digesterman on March 29, 2014, 12:13:50 PM
John you are getting gas and diesel turbos mixed up, here's a good article that explains the differences and why it is more of the gas/air volume on a diesel turbo that makes it work whereas on a gas turbo heat definitely plays a big role in it's efficiency.
http://www.wcengineering.com/articles/dieselturbo.html (http://www.wcengineering.com/articles/dieselturbo.html)
I know that article is written by a car turbo rebuilder, but why is it saying that diesel turbos only run 5-8 PSI? I get 26 PSI boost under full load on my 277 HP 6V92, a lot more than 5-8! Am I getting more boost than I should, or what?
John
You are right where you should be John pay no attention to that article the newer 60 series get into the 30# plus range they will idle with 5 plus #
I didn't even attempt to point out everything wrong with that article -- I wouldn't have known where to start!!!
Cheers, John