Advice on whether to re-route an external thermal bypass and how to do it

I own and operate a company in the Pacific Northwest that offers moss removal, gutter cleaning, window cleaning, exterior cleaning, and pressure washing. I never offer to pressure wash roofs, but I do dilute and disperse liquid moss treatment on roofs using the pressure washer and the soap nozzle (it sprays further than a Juice Box and it beats walking a roof with a garden hose and siphoning nozzle going to a 5gallon backpack of treatment).

I will try to keep this short as I do have a couple simple questions, but I would like to layout the scenario in case any members of the forum have some insights, advice, or suggestions about other aspects of the situation and my decision making process. I highlighted my questions in bold if anyone reading wants to skip the rest.

After a year of putting DeWalt’s 4000 PSI 3.5GPM model through moderate use, the power boost began failing causing the detergent injector to lose suction. I have decided to purchase a more reliable product and after talking to a few dealers in town have settled on a BE gas direct drive 4000 PSI 4 GPM, Honda GX 390, General Pump EZ4040G shown here:

One of the dealers I spoke with recommends that I let them reroute the thermal bypass so it drains straight out the bypass hose. The reason being that by the time the thermal relief valve were to open, the pump is already hot enough to be getting excessive wear and damage. What prompted the dealer to suggest this is the fact that the sort of work I do does sometimes involve several minutes going by without pulling the trigger on the wand. They said they do this modification for all their rental equipment and for several other contractors they sell to. Another dealer told me this was nonsense and the thermal relief valve is sufficient to keep the pump from overheating.

My first question whether or not it is worth it to reroute the external thermal bypass hose so it just drains out an open end for the sake of extending the life of the pump?

Now I found the exact pressure washer on sale from an online retailer. The dealer charges $100 more for the same model, they tell me it will be several weeks before they can get one in stock, and they do not offer to do the thermal bypass modification on pumps they did not sell directly.

My second question is that if it is worth it to reroute the external thermal bypass can anyone link me to a step-by-step walkthrough of how to do this?

My ultimate goal is to have the pressure washer on a wheeled cart, but it will remain mostly stationary in the back of my truck, positioned so that the rip cord and exhaust both go out through one of the side openings on the topper. If I rerouted the thermal bypass hose I would extend the house out the tailgate and let it drain onto the street.

Hope some of you can help answer these questions. Thanks for reading!

Please stop making repeated topics. The SPAM system is flagging your posts and is going to automatically kick out your account if you continue.

Most people here will probably tell you not to rely on your thermal relief valve to protect your pump. If you are going to be off the trigger a while, then you would be better off with a buffer tank that recirculates fresh cool water through the pump when in the bypass mode, or plumbing the unloader valve to just dump water onto the ground when off the trigger.

Whichever works best for you, but the buffer tank is the most common way of protecting the pump from overheating and it gives you the added benefit of having a sufficient water supply no matter what source you are hooked up to. The drawback for you might be that you would need a belt or gear drive pump to get the best performance from a buffer tank.

Sorry about the repeat posts, I thought it would increase the chances of experienced members weighing in if I posted my questions in the 3 most appropriate categories. I will not do this again and the other two topics have been removed at this point.

Thank you for the input Steve. It is already a tight tetris game in my truck bed so adding a buffer tank is not something I want to do especially since there is no apparent harm in letting the unloader valve dump water onto the ground.

Are there any tutorials available on how to do this? I have not done much plumbing, but I have done advanced truck maintenance using online walk-throughs on similar types of forums. I was hoping to find a writeup from a member who did this sort of modification and shared the process.

I don’t know much about your Dewalt machine, but the machine you linked to should have an unloader similar to this:

That blue hose directs water back into the inlet side of the pump when you are off the trigger. If you disconnect the hose where it connects to the inlet of the pump and divert it onto the ground, the pump always has fresh water coming in.

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Steve I really appreciate it, if you do not mind I have a one follow up question.

After disconnecting the hose and diverting it, what is the best way to plug that open connector to the pump inlet?

Depends on what kind of fitting it comes with but most likely there will be a brass barb there, so just replace it with a brass plug.

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Thanks again. The way the dealer rep made this sound there was more to the modification than this. I am glad to confirm it is this simple.

One last thing I was wondering is what type of thread sealant to use for pressure washer components like for using on that brass plug. I have a hose reel I just bought and the instructions say to use a suitable thread sealant. Are there grades to thread sealants?

There are different thread sealants but I personally use a couple of wraps of teflon tape and a light coat of blue monster pipe dope. Never had an issue. Some guys just use blue Loctite thread locker. Just remember MTO (male threads only) when applying any paste to threads.