Onan Cooling System Repair

[birdshill123]

Bill Pape has written an excellent article about redoing the cooling
system and insulating the generator compartment in his 88 FC. His
article provided encouragement for me to do the same. I have posted
some pictures in the photo section under " Onan Cooling System
Repair" and will add this post to the files area with the same title.

Unlike the earlier FC's, the Silver Editions (87 to 89) do not use a
Perkins genset. Rather they utilize an Onan DKD 8.0 powered by a
Kuboto diesel. It is not on a slide out and the compartment is very
tight due to space limitations. BB chose to use pyramidal foam for
sound insulation. This material is probably the best there is for
sound attenuation but it is designed for broadcast studios not for
the harsh environment of a diesel generator compartment that is
partially open to the outside and subject to diesel fumes, road
grime, water and dirt. Interestingly enough when I contacted BB they
still sell and recommend that foam. After 20 years the foam in my
compartment had deteriorated and was quickly falling off making a
mess of the genset area. Just checking the oil required a Hazmat
suit! Bill discovered that once you remove the genset there is a lot
of other remedial work to be done. I concur. I have divided the
article into 3 areas: tools and safety, parts required and R & R.

TOOLS AND SAFETY

Removing the Genset will require you to be under your Bird for
extended periods. This cannot be done without raising the MH , unless
you are very skinny. Looking at photos of the last RATS most of us
will not qualify as "skinny" ! I used the HWH jacks to raise the Bird
and then used jack stands, hydraulic jacks and an air over hydraulic
jack . My Bird was "in the air" for almost 4 weeks and never moved.
All the wheels were blocked. I keep a large fire extinguisher handy
whenever fuel is involved. I also used some 3M dust masks when
removing the insulation and glue. These are not the cheap masks that
come in a 50 pack. They are in a 2 or 3 pack and considerably more
expensive. Even better would be a real breathing apparatus.







Most of the tools required are basic mechanic's hand tools. Bill used
a wooden mover's dolly to hold the generator. I had one of those 2
wheeled dollies that you can find at Sam's and Costco. It has an
extra set of wheels so that it can be used as a 4 wheel cart. Better
yet would have been a pallet jack, motorcycle lift or even a
transmission jack. Removing the foam insulation requires a good stiff
putty knife. Most of it just falls off but lots of glue and dirt
remains. I washed the whole area down with Simple Green. Then I used
a knotted wire wheel on my 4.5 inch grinder. I was worried that a
clean surface would be necessary for the new glue to work. You need a
17 mm. wrench to remove the adapter at the exhaust manifold. I used
lots of PB blaster on some of the rusty sheet metal screws and the
tailpipe clamps and hangers. My shop is well equipped so I was able
to use air tools on stuck fasteners.


PARTS REQUIRED



We live in Mexico part of the year and that is where I did the work.
Most parts had to come from Tucson or elsewhere so I was very careful
about making sure I had everything that was necessary. You would not
have that problem. I am not a big fan of NAPA as their parts prices
are usually very high. I bought all the Gates hoses at
http://www.rockauto.com . They are about 35 to 40 % less than NAPA. You can
use this code over and over to get an additional 5% 8288812705329
The following are approximate prices:

Hoses and clamps $205.00
Motors and blowers $260.36
Insulation $300.00
Glue $64.50
Thermostat, gasket and fan belt $35.00
Rad repair $142.00

As well there is the cost of many shop supplies: sheet metal screws (
I used stainless), paint, engine shampoo, wire ties, nuts and bolts,
muffler clamps and hangers, freight, taxes and misc. The total
probably approaches $1100.00
Bill Pape posted the part #'s for some of the above but I will recap
and add some.

Motor for Cooling fan 4M099
Blower for Cooling Fan 4C592
Small fan w/motor 4C448
One inch Gates hose 24916 This is for a 5 foot length You need
3 sticks
Gates Rad hoses 21794 You will need 4 of these
Onan 90 degree hose CH22038 This is a Gates # for the one inch
molded hose . Onan wanted about $25.00
Glue 3M Super 90 spray adhesive

Note that I only paid $142.00 for rad recore. This was done in
Mexico. Figure on about $240.00 in the USA.

My parts sources were as follows:
Gates items http://www.rockauto.com
Blowers,etc. Grainger
Glue Home Depot
Onan OEM parts Curtis Service Corp. 908-561-3393
Insulation: Due to some special circumstances I ordered my insulation
through a Mexican company. BUT Steven Birtles is the best place for
this product http://www.capeinnovation.com
Wire ties http://www.happyterminals.com
Bolts, screws: http://www.boltdepot.com




R & R


In order to remove the genie follow these steps:
1. Drain the rad
2. Remove the lower front panel of the compartment and the rad
tank
3. 3. Remove fuel lines and cap ( fitting is JIC and available
at any hose shop, Parker 6 PNTX-S) . Mark fuel lines for proper
reinstall. Make note of hose routing.
4. Disconnect all the coach batteries and remove genset
battery. While you have the battery out is a good time to charge it
and then test. Mine had a dead cell.
5. There are 2 one inch cooling hoses that connect to the rad.
MARK these and disconnect from the rad.
6. Disconnect the wiring at the large cooling fan. Also
disconnect the ground cables at the back of the genset tray
7. Undo the exhaust pipe. I was unable to undo mine until the
genie was removed. I removed the muffler and tied the pipe up. Once
the genie was lowered I was able to use a long handled 17 mm wrench
and a cheater. I had sprayed the bolts for 2 days!
8. There is a plastic wire connector on the back of the 12 volt
control box that has to be unplugged.
9. As I stated I was using a dollie to hold the genset. I dumped
the air and used the HWH jacks to raise the MH part way. I then used
an air over hydraulic jack to lift the MH and slipped my dolly under
the genset. This jack is easy to control. Once the dolly was under I
SLOWLY lowered the MH until the genie was almost resting on the
dolly. I jacked one end of the genie up slightly with a floor jack,
removed the bolts and lowered onto the dolly. Did the same with the
other 2 bolts. The other jacks I mentioned earlier would have made
this much easier.
10. Next I jacked the MH up with the HWH and the air/hydraulic
jack. This allowed me enough room to stick my head into the
compartment and undo the high voltage cables. I made notes on the
wiring layout. BB had marked the wires with wire tags.
11. With jackstands in place I crawled under and disconnected the
2 cooling hoses from the rad.
12. Now the genie was wheeled out!!
13. Next I undid the 4 bolts holding the rad and blower assembly
to the MH . I used a floor jack under the rad guard.

The above is almost the easy part. The removing of the insulation,
cleaning , derusting and painting all the sheet metal, assembling the
cooling fan and motor, cleaning the genie, replacing the thermostat
onan hose and fan belt is very time consuming. I am fussy and used
all new hardware. Either stainless or Grade 5 plated. Do not try and
save $ by using other than the Gates wire reinforced hose. It is made
for applications like this. Any other hose would either kink or
deteriorate from the heat. I took digital pictures of most of the
assembly so that I could route the lines and hoses just like the
OEM. BB likes to assemble things without ever thinking that they may
have to be serviced some day. The electrical connections in the fan
box are ridiculous. Permanent crimps with some silly rubber condom
that fits over the wires. I cut them and cursed! I used male and
female extension cord ends for the new fan. My preference would be
twist locks but I am 65 miles from those types of parts. The fan only
draws about 3 amps. I removed the plywood firewall at the rear. Once
it is off you can see all the cooling hoses and how they are
connected. Again I marked everything. I used my bench grinder with a
wire wheel to clean up all the one inch hose connectors and the one
to one and a half inch adapters. I painted all the surfaces that were
to be insulated with flat black paint The new insulation can be cut
with an Olfa knife ( box cutter). I used the #M 90 spray adhesive and
applied 2 coats to both the insulation and the other surface. It
holds well. The rest of the job is simply reverse of the removal.

I primed the engine with the electric fuel pump and it fired right
away. I haven't taken it out of the shop to see if it is any quieter.

This is not a one weekend job. Many hours are required to do a good
job.

Thanks go to Bill Pape who provided lots of advice!!


Bruce
1988 FC35