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SWP5767 · 06-25-2013, 04:27 PM

Hello all!!

I have an issue with my 4 yr old Generac QP40G genny. This was installed by me when my Onan crapped out..

I followed all the manufactures instructions and this was not an issue to install.. The one detail they left out was which side of the RV it should be mounted on.. With this model its fully enclosed with an cool air inlet on the right and a hot air outlet on the left. Both of these are on the bottom of the unit. This unit is installed on the drivers side of the RV where the Onan was. When the RV is sitting, it will run for hours and hours with no issues. When driving down the road is when it will over heat and shutdown.

The issue here is, its recycling the hot air coming out from the front and sucking it into the cool air inlet towards the rear. The only real solution is to mount it on the other side of the RV.. I have no place for that so it has to stay put.

The question is, how can I keep this thing cool. Should I run a cold air duct to the inlet and pipe it away from the hot air coming out?

Thanks for looking at this post and look forward to your replies and advice.

Steve

gatorcq · 06-25-2013, 05:49 PM

Make a air duct system?

SWP5767 · 06-25-2013, 06:16 PM

I kind of did that. I was trying to find a pic of what I did so far, but it has not helped. I know it must be still sucking in hot air.

I will try and post a pic tomorrow of what I have so far.

Keitha · 06-25-2013, 08:36 PM

Are you sure it shuts down on heat
Check temps w/ an IR thermometer.
Sometimes a coil will quit when hot.
Any room for a 12 volt fan?
Some folks have used a bilge blower.
Insulated baffle 6"+ below genset to try
and re direct all that heat away.

Keith

SWP5767 · 06-26-2013, 06:07 PM

This genny has two protections in place. Over heat and low oil pressure. This is something that only happens during the summer when its 85* and up. In the winter, no issues at all. Coils on these little air cooled engines are pretty solid. I have never had to replace one.

I contacted Generac and they replied with " its possible its recirculating the hot exhaust air into the cool air intake causing it to overheat"

If this was on the passenger side, the cool air intake would be in front of the hot air exhaust. I cant move locations, so I will try and make a duct of some kind.

I did not have time and daylight to take pics of it today, I hope to tomorrow.

Thanks again for the replies.

Steve

SWP5767 · 06-27-2013, 04:37 PM

Ok! I finally took a picture of the underside of my genny. I hope you can see the text on the picture.

You will also see the little air scoop I put on the intake side.

RustyJC · 06-27-2013, 06:38 PM

Try using some rectangular duct to extend the cold air intake forward of the hot air exhaust.

Rusty

SWP5767 · 07-15-2013, 04:47 PM

Hello all,

I did some brainstorming with a mechanic friend of mine. In the process of doing that, I thought it would be best to exit the hot away from the cold air intake.. This is what I came up with..

From a privous picture you can see the 2"X12" space where the hot air exits. I used a 6" metal duct pipe and mounted it around that exit. It is open on both ends and 80% of the hot air exits straight out of the drivers side and the rest under the coach. That leave more room for the cold air to get it.

Here is a pic of what I did over the weekend

and another one.

So far so good. I put 3.5 hours on the genny yesterday. It was overcast and a little rainy so it was not a great test. It did not shutdown.. Im hoping for a really HOT South Florida day this weekend and test again.

Thanks again for your input and I will reply again when my next test is completed.

Steve

SWP5767 · 07-24-2013, 05:08 PM

Ok! I am naming this unit Generac-enstein! With all the ducting that has been done so far, It still shutdown twice last weekend on a not so hot day around town.

Keitha above has suggested a cooling fan. Well here it is..

I am using a piece of plywood for the testing phase of this modification. If all works out, I will mount the fan to the original door. The replacement cost of the door is around $100 so I don't want to make a 9" hole in it if this fails.

My plan is to wire this to the same source as my transmission cooling fan. I only need this to run when the RV is in motion so that makes sense to me and its nearby.

Here is a picture of the door when closed.. This space is about 2"X20" for it to vent thru. Im not ready to commit to making a larger hole in this door either. There is plenty of space around the door and unit for hot air to escape.

Im hoping for a hot weekend to test with and I will report back with the results of the latest Generac-enstein modification!

SWP5767 · 08-23-2013, 06:28 PM

Hello again! We went out for the weekend last week. Ole Generac-enstein never made it out of the driveway.. It was a hot ride to our destination.

A couple of weeks ago, I was anticipating that moment and started shopping for a replacement.. I wanted to get back to an Onan 4k. I found one about 160 miles away and the price was right. I picked it up for $225.. It is a 29 year old Onan 4.0 BFA if you are familiar with them. The PO had this on the tongue of a race car trailer and said it worked perfect. For 29 years old, he was right.. The oil was shot and very dirty, but for the price, I felt I could not go wrong.

Here are a couple of pics when I got it home.

I proceeded to clean it up and give it a nice tune up.. Replacing all the typical tune up parts and changed the oil. I started doing some ground testing with this unit to make sure it would hold up to the task. I installed a 30A outlet to the attached cord and plugged my RV into it.. I ran it for hours and hours with a full load with no issues.

Once the load testing was complete, I removed Old Generac-enstein and started prepping the area for the Onan.

One day after work I removed Generac-enstein.

You can see the way the access door is for the genny, I have to get the entire RV high up off the ground..

With the Onan cleaned up, its ready to go in. I scored this motorcycle jack from a co-worker for free. It needed a little work, but not much. It holds a genny perfect.

Here it is going in.

Here it is hanging on its own.

After finishing the install, I got the exhaust system installed.

and here it is completed.

I hope you enjoyed my Genny swap. Everything went as planned. One day for the old one to come out and two days to get the new one in.. That's after work of course.. It was probably 8 hrs total to remove and replace.

JRMEDPHYS · 08-23-2013, 06:53 PM

Nice work! Looks great!

My only bit of advice would be to make sure you extend that tailpipe beyond the edge of the vehicle to minimize exhaust fumes into the coach.

SWP5767 · 08-23-2013, 07:09 PM

Quote:

Originally Posted by JRMEDPHYS

Nice work! Looks great!

My only bit of advice would be to make sure you extend that tailpipe beyond the edge of the vehicle to minimize exhaust fumes into the coach.

Good pick up on that.. I plan too! I also want to get one that turns down a little to deflect some sound.

JRMEDPHYS · 08-23-2013, 07:15 PM

Quote:

Originally Posted by SWP5767

Good pick up on that.. I plan too! I also want to get one that turns down a little to deflect some sound.

SWP5767 · 08-07-2014, 04:33 PM

A little follow up on this install.. After the last year, I have put about 75 hours on it with no issues at all.. The generator turned 30 years old this year and I couldn't be happier.. I wish I had done this before the Generac install.