First off this is my first post and I am excited to follow the threads and conversations on this site.
I have a pretty much brand new Honda GX390 engine. The engine was sold as a John Deere unit with an AR pump on it. That pumped last all of about 30 hours and I am not looking to put the money into rebuilding a sub par pump. Clearly that is just my opinion, not looking to stir up the AR fans. I have ordered a replacement pump, the cat66dx 4000 4.0 and it’s arrives tomorrow. I have a question in regards to the set screw on the keyway. When I pulled off the AR pump this morning their was not a set screw in place. This is my first pump swap so I am not well versed at what is normal/required. I read online that not all pumps will have that set screw on the keyway. My question is this, when I install the new cat pump onto the GX390 will a set screw be included in the factory packaging? Second question—-since I was operation without one originally is it safe to move forward without or will I need to hunt one down tomorrow to get this thing back up and making me $$? I appreciate all the positive feed back in advance.
So, I personally don’t think you need a set screw if you have a key way. If you do use a set screw, remember, one screw will keep a washer or bushing in place, but to keep a pulley in place you need two 45°s (@Infinity) apart.
Thanks man! I really appreciate you taking the time to answer. Is there anything else I should be aware of? Any tips or tricks? Bought as GX390 with an AR pump on it,3800 psi 4 gpm and replacing with Cat 66dx 4000psi 4 gpm. Hoping to just bolt on, add oil to pump and be ready to go! Is it as simple as it appears? RPMs and idle will work under new pump?
You will need to set the unloader. The last three pages of the following document give instructions on how to set three pressure-trapped unloaders.
I’ve seen described on this forum a method to set the unloader without using a pressure gauge, based on the amount of flow out of the unloader bypass hose. Others on this forum can better describe this method than I can and also whether this method will work with a pressure-trapped unloader.
Yes…4 bolts, no need for set screw. Takes 2 minutes to swap out. Unloader comes pre set, go ahead and check it and adjust if needed. Use search bar on setting unloader
Man I can’t say thanks enough. I was a little bit nervous going into it only because I’ve never swapped one out before but I now feel like it’s going to be a breeze. I’ll update tomorrow evening once installed and tested!
I’m not knocking what your saying because you always give good advice, but I have never bought an unloader that was preset. But, you might be talking about one that comes on the little cat pump. If so, I stand corrected.
Yes, the one that comes bolted to it should be preset. I should have clarified with him, but if he’s running a CAT I doubt he’s using a fancy unloader with a block (:
The above attachment from Pressure-Pro says to put silicone around the engine shaft and key. Instead of silicone most people use a generous amount of anti-seize compound. I use marine grease, which is available at NAPA Auto Parts with the other cans of grease.
Funny, you mentioned that as I just had to do a oil adapter the other night after loosing a Martin pulley on my Winco. I should have known better because it only had one set screw. I pumped out about a cup of oil since it chewed it back all the way to the galley. I never heard a thing since I had my ear buds in. Luckily I knew the second I lost my heat and went to check things out or I went have lost my first engine.
My buddy had a 66DX. The set screw that’s there is more like a cap screw. There is a window in the mounting flange that you acess to loosen and tighten it.
I run 3 of these, one 6DX and 2 66DX’s. I have been washing 6 semi trucks weekly for 5 years with the 6DX, by the way it’s over. 20 yrs old, never one single issue ever with that pump, and using the 66’s for several years no issues. Throw away the stock unloaders, and replace with good ones, and run a bypass line to put tank or just dump it under your trailer and they will last forever. Also put your intake and unloader on opposite sides of the head, this was recommended to me by a technician at CAT. I run the 66’s in tandem regularly for nearly 9 gpm for surface cleaning. Never one issue. I wish I understood why most here hate on these pumps. I believe some of the hate comes from the stock recirculating unloader, and people letting the run too long off the trigger. They will get to 212* QUICK like that. I run mine at 3600, WOT for the 390 and get 5.1 to 5.4 GPM, this also recommend by the guy at CAT. If you have any questions or issues with the cat pumps feel free to ask or pm me.
@ShinedUP— thanks dude! Everyone has been so helpful. You never know with these forums—sometimes people are great and then some people are complete garbage as can be found in most saltwater/reef forums. Anyway, back to topic. I feel like the CAT pumps are a great product as well. Your story gos to about a dozen others I’ve personally seen or heard of where the pump just keeps on with no repairs needed for years. Unfortunately my package is still not here yet due to a security check”. It is supposed to be here this evening now and I will update the post when it arrives—-disclaimer—I plan to post some pics of everything for those that may be interested if the forum will allow for the uploads.
Innocentbystander: Thank you. I just read up on the blue springs and now better understand what you’ve said on this forum about setting the unloader based on the amount of flow out of the bypass hose.
