GM Questions

I am looking at buying a Denning Denflex bus to convert into a motorhome, (another one!) It has a 300hp V6-92 GM and Alison auto. My question is does anybody know of any issues with this engine. The only problem I know of with this particular engine is the Jake brake is not working due to a crook switch inside the rocker cover. How difficult a job is this. Any comments appreciated.
Ray

Hi Ray,
Each bank of the engine will have a 'Master' jake brake which has an electric solenoid fitted. Replacing it is pretty straight forward. Do the Jakes work at all? If it has a faulty solenoid then the jakes on the opposite side of the engine should still provide some engine braking. If the jakes don't operate at all it could also be the switch that is fitted to the governor instead, or maybe both solenoids under each rocker cover, or another faulty switch (mine has one fitted to the clutch pedal too - so the jakes stop when you press the clutch in)..

I have attached a photo showing underneath the rocker cover with the solenoid position marked with a cross, and also one of the switch on the governor.

I'm sure Basil or someone else will be able to give you some more info.

Regards
Stuart

[img]www.smcswainengineering.com.au/jakes.jpg[/img]
[img]www.smcswainengineering.com.au/jakes2.jpg[/img]

G'day Stuart
As far as I can tell by what I was told the Jake is not working at all, so perhaps it may not be the switches in the rocker covers. Looks like I may have to find out if off the owner if it is working at all.

Hi Ray,

Stuart is right in what he says.
If you go onto the Jacobs Brake website you can download a manual for the 71 / 92 Jake brakes. There is a good trouble shooting section.
www.jakebrake.com/support/technician-guides.php
Most common problem Ive had with them the power supply, either the clutch switch or the buffer switch located on the governor housing being out of adjustment.
First thing though is make sure you have power to the Jacobs on / off switch on the dash. If you have turn it on and check you have power to the clutch switch. If you have then check you have power to the buffer switch and so on.
Have a read of the trouble shooting manual and im sure you will find the problem easy.
There is also parts and install manuals on the Jake site you can download.

Basil

Ray
GuddayM8

Sum xcellent advice from above
the 92 series 1st V: twaz the white painted engine
after sum updates they went to green engines
n after sumore updates the last V: Silver was introduced



the engine brake should not B turned on n used while driveing till the water temp of engine is @ operating temp
http://tbn3.google.com/images?q=tbn:vEsjLnB0AQzvHM:

with the engine shutdown n rockercover removed U should B able to place a probe light from the JB Solonoid to earth then by pushing back on the rack (Injector linkage) it will push on the buffer micro switch n light up the probe light n also U might hear the solonoid clik in
The Buffer MicroSwitch can B finely adjusted to cut out when U apply the go pedle or @ idle revs
I have @ one time had the Buffer microswitch so finely adjusted th@ it cut out when it was the xact revs to change down in a skip shift
(eg: 12-10...11-9 etc etc
hope this helps
n let us all no how U go

Also
Got An Also

Stewy GuddayM8

FWIW
if U didn't no


cya


[ch9787]

Very sneaky of you Swishy, Mr jake shifty.
Did you manage to get him adjusted just nice without the governor hunt or lope at idle ?.....If ya did your clever. Should have been a mechanic not a steering wheel attendant

Ray, if you have any trouble with it give us a yell. There simple and parts are available.

Basil

Bazzr
GuddayM8
SMe again
LOL
Didja no FWIW
we were the 1st in Australia to fit Jacobs engine brakes to our Kenworths n 'B' model Macks
I soon lernt th@ jakes mainly fail from wireing
the wires get hard n brittle under the rocker covers n hard to keep 100% contact with solonoids

LOL



cya


[ch9787]

Ray,

Got all excited about the Jakes not working and didnt answer your core question : My question is does anybody know of any issues with this engine.

I reckon the 6V-92 is one of the best Detroits's they made. My opinion offcoarse.
Make sure you run the correct mono grade 40wt oil in your GM....ie Castrol Tectoin DD-40.
Dont be tempted to tip some supercheap multi grade in it. It'll end up a big snotty mess and in time you will end up with it in pieces fixing it.
They are designed to work so dont spend to much time in the driveway sitting and listening to it idleing with ya mates having a beer.
This will also make a snotty mess.
When you are out and about make it work. Dont drive it like you hate it just make it work.
There isnt any mechanical problems with them to look out for. No more than any other diesel.
Clean air, clean fuel and good oil and your away.
As with all diesels a tune from time to time keeps em in good nick.

Basil

Thanks for all the info fellas. I have only had dealings with 3+4 cylinder 53 series hence the queries. This one had a $20,000 rebuild of the engine and auto some 9 years ago and only does 50ks a day on a school run through the hills. I have been told there are no leaks or breathing from the engine but it does tend to run at the upper end of its temperature range and could probably do with a radiator clean, so at this point in time it sounds ok. Just waiting for a mate to send some pics to me to see if it is worthwhile.
Ray

Hi Ray How did you go with the Denflex? I was going to buy one of these for the same reason,probably looked at the one you speak of, but recently decided to go a Denning Landseer. A couple of extra wheels and a bit more height but more room for everything. I found a few cheap ones of these if you are interested?