When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Thanks for all the info Castillo! Much appreciated!
I rarely carry any passengers in this van, and the rear seats have actually been removed. I run a small part-time handyman business and the van is very practical for carry a few tools or for picking up materials, but it is rarely loaded with more than a couple hundred pounds.
Like I said earlier, I do have a utility trailer that I use once in awhile to pickup larger materials or to haul away yard waste or stuff for the dump. But I live in a fairly small town, so trips are short and I will be mindful of the weight I'm hauling if I can't get the oil cooler put back in service.
I also live in a very flat part of Ontario and the only hills are the highway overpasses, lol.
I think you can save yourself the challenge and just by-pass that cooler. Based on this response from you it's not needed. 'But so, I don't get slammed with bs from any member I would suggest dure cold winter months to do the most basic common-sense thing for decades is let the engine warm a little after a cold start before driving normally.
Another brief update that might help someone else in this situation. I stopped at the Mazda dealer on my way to return the Dorman part. They can get the hose that steps up from 5/8" to 3/4" and the part number is AJ03-14-522. It's about $55CAD and would take a week to get. I might go with that route, but the metal tube that hose attaches to is really rusty on my van. I tried cleaning it up last night with a wire brush to get a better idea of its condition, but it's hard to tell because it's in such a tight spot and most of that tube runs behind the catalytic converter. I can definitely see some rust pitting and I'm not sure I want to gamble on that pipe lasting much longer. So I think I'm going to stick with the bypass for now and picked up some 3/4" heater hose and a 5/8" to 3/4" connector to join the hoses. I also got some rubber caps for the old cooler lines. There is still some coolant dribbling out of the old lines and I thought something was leaking until I figure out where it was coming from. I also don't want anything getting in there in case I decide to reconnect them later.
I should have mentioned earlier but not always suggesting DIY methods in any capacity as a rule (I tend to go by the service procedures) that a trip to a local auto parts store and looking through the large stocking hoses you may find surprisingly a few that have 2 sizes (not uncommon) on one hose like your hose but may be longer and simply needing to be trimmed to length..
If any metal lines have rust inside, they should not be reused as the rust will continue and contaminate your coolant.
I'm back for another update... I bought some 3/4" heater hose and a 3/4-5/8 straight connector. I put the 3/4 hose on the water pump, but it needs to make a 90 degree bend to connect to the 5/8 heater hose. I tried doing a long gentle bend, but the hose kept kinking and was also rubbing on the motor mount and other things. So I wasn't happy about that. I couldn't find a 3/4 to 3/4 elbow locally, other than some cheap plastic ones made for watering systems and I didn't trust them for this application. While I was searching online I saw some videos about making custom heater hoses by heating them up and using tubing benders to avoid kinking. So I tried that, and I think it may work. Once I put the coolant back in and ran the engine for awhile there was a small kink on top of the hose, maybe more of a dimple than a kink and not nearly as bad as before. I don't think it will restrict the water flow and I'm going to run it like this for awhile. If the hose kinks again I will be looking for a 3/4" hose with a factory 90 degree bend in it.
While I had everything apart again I also tried to remove the old hose assembly. I thought if I could get the old one out, I could inspect the rusty tubes to see how bad they really are. And if it came out, a new one should be able to go in if it comes to that. I managed to get the clamps and the hoses off the oil cooler, with much difficulty, but there was no way I could remove the assembly. The clamps that hold the two rubber hoses to the metal tubing on the oil cooler side seem to be the problem. They were getting hung up on the exhaust manifold. Because of where those clamps are located, I couldn't see anyway to access them. When I tried moving the hose assembly, the metal tubing was also getting jammed up against the waterpump outlet. So I had no choice but to reconnect the hoses back to the oil cooler and leave it in place, but disconnected on water pump side.
So it seems to me like it might be impossible to change the hose assembly without removing the exhaust manifold, catalytic converter, etc.
Last edited by streetcore; Aug 3, 2025 at 09:33 AM.
There are all kinds of alternatives for a 90* fitting
This has been my go-to for odd ball items for a few decades. McMaster-Carr
It does read like you are slowly getting things worked out
