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Q: Kevin Coates wrote: Hey Mark, Thanks for sending me the "How To" info to install a threaded plug to stop the leak on the head. My question is, did you have to drill the hole out and tap it. Or is there a tap and plug that will match for this hole. I believe that the hole size is .240". I could sure use some help on this one. The tapping part looks pretty easy, but I just can't find the combination to use. Please let me know. A: This question is carried over from a discussion on the LCML and some personal Email that I have had. It deals with a problem that I have been warning folks about for a while. I discovered it for the first time when I suddenly had a high pressure oil leak while on the trail. The problem, syptoms, and solution are as follows... The 2F and 3F engines supply oil to the rocker arm assemblies via an oil galley in the block wichopens into a small cavity in the headgasket (the teardrop shaped opening wirth the copper "O" ring for those who have had the head off) This opening in the headgasket allows the oil to travel over about an inch to the bore of the third headbolt from the rear on the passenger side of the engine. The oil passes through this bore (between the head and the bolt itself) upward a couple of inches to where there is a small passage drilled through a boss that runs forward across the top of the head to the #4 rocker arm pedestal (this boss is clearly visible if you remove the valve cover. From there it passes up through a passage in the rocker arm pedestal and on to the rocker arm shaft assembly. This is all well and good. The problem arises because Toyota apparently decided that one of the few cost cutting approaches they would take, would be to use a press in plug, rather than a screw in one to seal off the external port left when the passage was drilled from the head bolt bore to the rocker arm pedestal. If you look carefully, right beside the mounting hole for the air cleaner assembly on the side of the head, you will see a small protruding section. On the rear side of this (about a 45 degree angle from the side of the head), there is a small (6mm, or .236 of an inch) barely noticable recess where the plug is pressed in. As the years go by, the miles roll up, and the engine undergoes uncounted heating and cooling cycles, this plug can work loose. Sometimes the result is a seepage of oil that is difficult to track down, but leaves the side of the engine perpetually grimy. The bad ones are the ones that actually pop out, resulting in a high pressure stream of oil out of the side of the engine. I have discovered, that in a pinch, a press in zerk fitting will fit tightly into the resulting hole. Packed full of epoxy and allowed to cure, this can provide a long lasting (but still temporary) fix. Simply filling the hole with epoxy will probably work, but I would never be comfortable with it. You could press another tiny plug in, but this just isn't the way to really solve the problem. The best fix (assuming you are at home, and not on the trail when you discover the problem) is to drill and tap the hole for a screw in plug. This can be done with the head on the engine. First remove the valve cover, and the headbolt that the oil flows around. Insert a cloth, a cotton ball on a string, a soft rifle/shotgun bore swab, or some other material to prevent any metal flakes from falling into the bore. Then use a "F" sized drill bit (.257 of an inch) to drill out the short passageway between the head bolt bore and the exterior of the block. Once it is drilled, tap the hole with a 5/16-18 tap. An allen head screw can then be threaded into the hole until it is flush. Coat the threads with epoxy before installing the screw. Reinstall the head bolt and the valve cover, let the epoxy set up, and you're ready to go. This small modification is a good idea to do or have done to any 2F or 3F engine, even if it shows no sign of leakage. I have seen them fail with no advance warning. No seepage or any other sign that the plug was about to fall out. Of course there are thousands of the engines out there tha have never had a problem with the plug, anf probably never will. But there is now way of knowing which class your engine will fall into. Q: Robert Granier wrote: Well Mark, I emailed you previously about the cheapest way to lift my FJ60, and I apreciate your quick response and your patience with my amatuer questions (I realize that for someone like yourself its about like a doctor seeing another cold). I was wondering if you can give me some more infor on the lifts you suggested, the add-a-leaf, and the shackle extension. I had read somewhere that when you use extended shackles, you have to add shims to realign the axles, because you're only dropping one end of the spring, is this true? Again, thanks for the help. A: This is true, but only for the front end. When you use extended shackles, you are changing the angle of the spring in relation to the rest of the truck (and to the ground as well, but that isn't really a concern. This changes the caster of the front axle, and adversely affects your steering and vehicle handling charateristics. The solution is to add tapered shims between the front axle and the springs to return the axle to it's original position. You don't have to worry about the rear end, because the rear wheels are aligned neutreally, and the rotation caused by the extened shackle doens't change any alignment factors. In an extreme case you could theoretically extend the shackle enough to cause problems due to the misalignment of the pinion angle. In the real world this isn't an issue, as it would be unsafe to attempt to mount shackles that were long enough to bring this concern into the picture. Q: Bret Stastny wrote: I have recently purchased a 1977 FJ40 and I am having low oil pressure problems. The oil is fresh with less then 50 miles on it. When the engine is cold the oil pressure is fine but as the engine warms up the pressure drops. When the engine is idle the pressure is almost at the bottom the of oil pressure gauge. But when at driving speeds the gauge reads at the bottom of the "normal" range. Is this a tell-tale sign of something? A: It is pretty normal for an engine to show higher oil pressure when cold than when warm. The oil is thicker, and so resists flowing through the oiling passages, and out of the relief valve in the pump. Once it warms up it flows much easier, as it is thinner. On a fresh new engine there will often be enough resistance to flow to keep the pressure up over the relief valve setting at all times. Then you will see little fluctuation at all. On an older engine with larger clearances in the bearings due to wear, the oil can pass through the system at low flow rates (slow engine speeds) quickly enough that the pressure doesn't buold as high. I have learned, that the factory gauges are not always real accurate. Since the oiling systemis the weakest point of the Cruiser engines (especially in the F engines), I strongly reccomend an aftermarket mecahnical oil pressure gauge with accurate numerical markings. If your gauge is reading accurately, then you are looking at the indications of tired bearings. Idle pressure at the bottom of the gauge, and cruiseing speed pressure at the bottom of the "normal operating range" is not a good thing. Increaes clearances in the bearingds translate into greater "impact" on the bearing with each rotation of the crank, and a more abrupt unloading and loading of the bearing. it also allow lower pressure as the oil passes through, wich reduces the oils ability to resist the shearing forces of the rotating surfaces. What this all boils down to is that with gentle treatment, light loading, few high rpm bursts, and NO overheating incidents, your engine may still last a long time. HOWEVER, it could also be ready to seize or spin a rod or main bearing at anytime. For safe operation, you want to see AT LEAST 10 psi of oil pressure for every 1000 rpm of engine speed. 15 psi per 1000 rpm is better. Send your questions to Mark at cruiser@rockcrawler.com |
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