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jebsays · Posted: Wed May 11, 2011 4:05 pm Post subject:

Be aware that anything you use that lifts the head from the deck will decrease the compression ratio - depending on the thickness, you could lose up to a couple of points.

Chef Lefty · Posted: Wed May 11, 2011 7:41 pm Post subject:

rodandroll · Posted: Wed May 11, 2011 11:24 pm Post subject:

The best suggestion I can make is to go online and order the factory service manual. It will give you parts numbers, take you through head tear-down and replacement step by step, with pictures and tell you the right compounds, sealers, etc... to use. I know on my 1998 Johnson 150 there are other things you are also supposed to attend too when pulling the heads.

I have always order the factory repair manual for every outboard I have owned and they have saved me significant heartache, time and money.

rodandroll · Posted: Wed May 11, 2011 11:27 pm Post subject:

Capt Mike Singleterry · Full Grown Flour Bluffian Joined: 07 Mar 2006 Posts: 2728

Hey t, I forgot to ask you.....when you replaced the water pump did you just replace the impeller or did you replace the all the parts with a kit?

If you just replaced the impeller that might be your problem. The wear
plate could have some bad groves.

I still want to look at the easy things, before you tear it down.

Mike

Snapperslapper · Finger Mullet Joined: 12 Jun 2007 Posts: 26

I have worked alot on a 60 deg V6 same block just 2 more cyl. if you pull the heads take them to get reserfaced at a outboard machine shop, most car guys will do a fair job but a knowlageble machinist can fix the heads if needed. Clean the grooves for the orings well and the surface of the block and heads. tap all the holes for the bolts also. clean all surafces with brakeclean and let dry. use permatex #2 on the orings and flat surfaces to seal the job and nothing else. Dont use silcone or like products or make any kind of gasket. As far as water leaking put the motor on a hose and run it for a while idling. shut it off and let the hose build pressure for about 10 min then pull all plugs and look for water on them. Have someone or use a remote stater to turn over the engine to ckeck for water in cylinders. if you still have your old thermos, cut the metal popet off the top to make them a restrictor and put them in the place of the new thermos and run the boat. You may have grass in the new themos causing a problem. You can cut the tip off the thermos where the holes are to let grass pass the engine. Check the pick up screen for grass. NOTE if you pull the head, replace the seals for the thermos in the head and be SURE you place them in the head like the old ones come out or you will have problems. Put some permatex #2 on the rim of the seal when you install. Get some marine neversieze (zinc based) it will be white instaed of silver. Plain neversieze is alumimin and so is your block and it will cause problems. you can get the orings for the heads at a bearing house but you need viton orings for the heat but the seals for the thermos will have to come from OMC

Snapperslapper · Finger Mullet Joined: 12 Jun 2007 Posts: 26

my 60 deg will not build up more than about 20 psi but gauges can be off. Is the motor pissing correctly? check for grass in the pisser, you can run the motor with out the "nut" for the water hose, it just makes the little stream, and provides no cooling help at all. Does the motor heat up fast, like as soon as you start or over time. Can you idle around. If you dont have them you need to intall twin temp gauges, one on each head. If you are just going off the alarm for heat that could be the problem. If you have or do install twin gauges look and see if one side is hot and the other is not, thats the problem side. Mine with thermos installed will run about 160-180 in the summer in the bay, lakes are cooler. Dont be alarmed if the heads are differnt temps 20-30 deg differnce as long as not over 190 deg. Are you using the oil injection? mine toasted the engine now we mix oil and runs good for 8 years. The water pump kit is important as listed above if you just changed the impeller. Did you grease the impleller at install? you can rip the fins off if you put in dry. post back here with the heating times of the motor and ill see if i can think of any other things. I have never seen a prop heat up a motor but theres all ways a new thing to cause problems.

Snapperslapper · Finger Mullet Joined: 12 Jun 2007 Posts: 26

I always for get the simple stuff, get a compression tester from Autozone or and other store and check the compressoin of each cylinder. Pull all plugs and check each one, dont care about the number just look for "like numbers" you dont want more than 5% differnace between cylinders but may have 10%. if you have more than 10% differnce you should check that cylinder by pulling the head and looking for damage in the piston or cylinder. If 2 are low next to each other there is you head leakege if the motor cylinders look good. 120 psi is great but ive seen 80 psi on all cylinders run for years to come. Check the numbers, post them up. change the plugs when you check comp, autozone can get the plugs for like $2 each

t · Pony Mullet Joined: 07 Jun 2006 Posts: 70

Wow. Lots of advice. Thanks to all. To address a few suggestions/questions in the order they were asked: I will not make any gaskets myself if i tear the heads off, i will go back with OEM parts and permatex and make sure the head surfaces are true; I agree, it is God's country....however, my paycheck comes from Zachry in SA, so i live in SA; factory service manual is a great idea but the knowledge on this site is likely almost as good; if i pull the heads i will make sure to clean passages properly even though when i changed thermostats the passages i could see looked very clean; I changed all parts associated with the impeller (plate, housing, key, o-rings, gaskets, etc); thermo seals will be replaced if heads are pulled; head bolts will be tough since they have never been out; good flow of water out of indicator; takes about 5 minutes after start up for engine to automatically idle down which indicates power pack and temp sensors are working correctly; last time it overheated was at about 4500 RPMs for about 10 minutes; pressure gauge could be jacked but reads about 10 when at idle, then goes up steadily with RPMs....low water pickup makes a big difference; no actual temp gauges; oil injection was taken off last year. My next step is still to retorque heads, change props and work it like a rented mule. If it overheats, then i will pull the heads.

Thanks again to all,

T