There are a lot of jet boat owners who complain about unusual oil pressure behavior while their 460 engines are running at sustained rpm in their vessels. There are a number of reasons why such unwanted oil pressure behavior may occur, but with the Milodon jet boat pan the complaints seem to be common.
These are simple, basic, but functional oil pan changes. The mods are simply for improved functionality of the oil pan. Performing more extensive mods, detail work, etc, to this oil pan design will cost far more in labor and materials than the final value of the finished oil pan upon completion.
Over its years of production, the Milodon 460 jet boat pan has seen some changes in its design. These design variations over the years are likely playing a part as to why some users have unusual oil pressure symptoms while others do not. Pictured here are two Milodon 460 jet boat oil pans side-by-side, with their windage trays removed. Note that the trap door/baffle of the pan on the left traverses the entire width of the pan, while the trap door of the pan on the right does not. Obviously, during deceleration the oil pan on the right cannot retain all of its oil at the rear of the pan since the oil has an open path to flow around the baffle and back to the front, thereby starving the pickup at the rear of the pan.
This next view shows why one pan's gated baffle traverses the entire width of the oil pan while the other does not. The earlier pan's baffle used to be taller, and it was necessary to leave an opening at one side so that the pickup tube could pass alongside the baffle. By lowering the overall height of the baffle in the later pan, the pickup tube could now pass over the lowered baffle, which in turn allows the newly lowered baffle to be full-width and better retain the oil in at the pan's rear and around the pickup.
In this view of the pan I've drawn the approximate location of the pickup box. Obviously, as oil flows forward on deceleration, the pickup box will be starved even though a small amount of oil is retained in the gated feature of the pan.
The fix for this is to fabricate and install an extension of the pre-existing baffle and "bridge" the open gap in the pan. This extension should have its overall height be that of the newer gate design...in other words, make it lower so that it does not interfere with the pickup tube (the pickup tube will pass over the newly installed extension).
Weld it in place. Remember to first remove the gold irridite prior to welding. We filled the rear of this pan with water and it stayed in the back of the pan. The only place it could exit is through the pickup tube.
This next picture is an overhead shot of the oil pan with its windage tray installed. Note that the windage tray does not directly protect/cover the area where the pickup box sits but instead that area remains exposed to windage. Also, I am of the opinion that the upswept windage tray does more harm than good--while the upswept design does allow for louvers to be punched in to act as scrapers, I also think the general shape of the tray supports windage by directing the falling oil and turbulence back toward the rotating assembly.
The fix for the windage tray was to fabricate a new one from a flat piece of 14-gauge steel. This new windage tray covers the pickup area more effectively, and also hugs the oil pump more closely, etc. It's flatness allows oil currently caught up in the windage to slam against the side of the pan and then drop to the sump. The flat windage design also helps hinder windage more than a radiussed tray which I feel directs/re-introduces those forces back to their source. The original windage tray and its zeus fasteners and clips are removed, and the new flat windage tray is held in place with stainless hardware and ny-lock nuts. This particular modification is competely reversible back to the original tray design.
The end user reports that his oil pressure no longer drops when he agressively stops the boat, and that upper rpm oil pressure is stable.
Simple, basic, bang-for-buck, effective, and anybody can do it.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Performance Boats Forum
2.1M posts
41K members
Since 2007
A forum community dedicated to performance boat owners and enthusiasts. Come join the discussion about offshore racing, performance, modifications, builds, classifieds, troubleshooting, maintenance, and more!