Compression on johnson outboard motor?
i don't think 80# is too low on a stock engine,especially if you didn't warm it up first. i check them every day and they range between 80 to 100 #. the fact that they are even is a good thing.you don't say what year it is, but johnson had a low compression v6 that was about 6to1 compression ratio for a few years. as the other post stated,warm the engine to operating temp, remove all of the plugs, open the throttle to wide open,and be SURE it's in neutral or remove the prop if you want to keep all of your toes. use a remote starter button or a jumper wire, yellow/red to battery + if you don't have a helper to turn the key.
How good is a Johnson GT 150?
I am planing on buying a 28 foot pontoon boat soon and i have two different motors i can put on it. I have a 1996 75 hp mariner and a 1989 150 hp johnson. I have used the 75 hp alot on a 15 foot ski boat but i have never used the 150 hp. My question is if i run the 150 hp at a lower rpm will it be as fule efficiant as the 75 hp going the same speed at higher rpm?
Johnson outboard timing adjustment?
timing marks and piston position are two of the most basic things that you learn before working on any engine(rotarys excluded).if you don't know this,i doubt that you are up to the task of timing your engine,but i have a little extra time this a.m. so i'll try to go over the basics.the flywheel is numbered in degrees (360 in a circle). when the zero is lined up with the timing pointer,the number one piston(the cylinder closest to the top of the engine) should be at the top of it's stroke(close to the spark plug hole).this is called top dead center(tdc). since the timing pointer is movable,it's best to check to be sure that the piston is EXACTLY at the top of it's stroke when the zero mark lines up.thats why you need the "special" caliper (dial indicator). if it was properly adjusted,and hasen't been bumped or moved,you can skip this step. you WILL need a timing light for the next step.most outboards idle with the timing adjusted somewhere after tdc.(usually about four degrees)so that the spark happens as the piston is moving down.there will be a link,rod,etc. to adjust this.mark the correct number on the flywheel(check the specs),aim the timing light at the flywheel and pointer,and adjust the link to align the pointer with the number that you marked on the flywheel while the engine is running at idle, light connected to the number one spark plug wire.now that the base timing is set,you need to set the total advance timing.to properly do this the boat needs to be in the water,and you will need two people.mark the flywheel at the proper number(usually somewhere between 28-32 degrees BEFORE tdc, check the specs).adjust the total timing link,rod,etc. to align the pointer to the mark that you made.if you try to do this yourself(i don't advise it) be VERY careful,as you will be very close to a 25 lb frisbee with teeth turning at about 5000 rpm.the total advance timing is critical, and if improperly done,will destroy your engine.i strongly reccomend that you take your engine to a shop to have this done.once properly adjusted,you should never have to touch the timing again.also there are other things to consider,such as throttle cam roller alignment etc.be very careful or you could die,or even worse,get hurt.
Can 5W-40 oil harm the engine if the manual says use 10W-40?
In a nut shell: you should always use the oil viscosity recommended by the vehicle or engine manufacturer. If there are any alternative oil viscosities allowable then they will be listed in the owners manual for the vehicle or engine …and there may be caveats with regard to the range of expected daily temperatures.Will 5W40 cause any harm? Maybe. It depends on things like the general, daily ambient temperature and the design parameters of the engine itself. Typically lighter weight oils, like the 5w40, are used when the weather is cooler than say in the heat of the summer …that would be when the 10w40 would be used. Check with your owners manual.This sounds like oil for a motorbike. Most modern car engines don’t use 10w40. Small engines used in motorbikes are typically air-cooled and, to a much greater extent than water-cooled engines, they use the oil in the crankcase to also cool the engine …to draw heat from the hottest parts. In addition, motorbike engines …4-stroke motorbike engines (where you don’t mix the gas with oil) use the crankcase oil to lube the gearbox and the wet clutch used in these engines …areas that also create a heat load for the oil. If this is, in fact, oil to be used in an air-cooled engine then stick with the 10w40.
Will driving with a oil leak in the valve cover gasket hurt the engine? If so, how can this be prevented?
Is it an oil leak or an oil seep? Does oil run down the side of the engine leaving a clean trail as oil drips on the ground? Or does it just form a nasty, mucky oil-dirt combination that slowly builds?If it's actually a leak, get it fixed now. You can lose sufficient oil to starve the engine and cause premature wear or even failure. On top of that, you have an oil slick being left wherever you go, oil is probably dripping on the exhaust causing nasty fumes (not to mention a potential fire hazard) and you are having to spend money on oil that is just going to hit the ground. Not to mention it's not exactly good for those plants by your driveway to have oil washing into them.If it's a seep, don't ignore it. Get it fixed. If you have to wait a week or 2 for financial reasons, that's understandable, but don't push it out too far as it can develop into a leak. In addition, the dirt, cottonwood fluff, dandelion seeds, etc that can get stuck in the slime will do a few detrimental things. For one, it insulates your engine raising operating temperature a bit. Most cars engine oil relies on the side of the block and the oil pan to radiate heat away. Remember, oil functions as a lubricant, cleaner, and coolant! If the block and pan are caked over in grime, it is harder for the oil to transfer it's heat through the pan and into the air. This grime can also pose a serious fire hazard. Not fun.