'91 Mariner 200hp performance / oil leak.

[RatherBFishing]

A couple months ago I purchased a '91 Procraft 200 Pro. bass boat with a Mariner 2.5 liter 200hp. The seller said he had it out only once ever and had it about a year. He said he was able to get up to 70mph. I am only able to get up to about 55 or so per the speedometer, about 47 per gps. I guess that would be problem #1. #2, I am having a terrible time getting it up on plane. Even trimmed all the way down, the bow goes up in the air and about the time I start getting a little speed, the prop starts cavitating and I have to back off the gas. Once it does get on plane, it stays there and performs pretty well as long as I keep the speed up. It seems to drop out of plane at about 18 mph though and I would think it would stay on plane slower than that. <br /><br />The engine doesn't seem to dog or anything, but problem #3 is that it idles really bad. It kinda "chugs". Nothing smooth about it. It starts well but when it does it puts out a cloud of smoke for a few seconds. <br /><br />Finally, problem #4 is that just today, for the first time I noticed oil dripping from a hole in the lower unit. I assume the hole is a water in-take, but it is in the front of the lower unit rather than the side.<br /><br />Obviously, I am new to boats. By reading through some of the forums here, I suspect the motor may be too low and the exhaust is in the water causing the bad idle and possibly the smoke. It does seem really low to me. Standing still, the top part of the motor is practically sitting in the water, way over the exhaust.<br /><br />I'm not sure what to do about getting it up on plane. I here talk of the "motor being x number of inches below or above things" but I don't recognize those terms.<br /><br />Is it possible all my woes would be solved by raising the motor or getting a jack plate? Could that even be the cause of the oil?<br /><br />Also, what should the max RPMs be on this motor? I don't want to over rev it.<br /><br />Thanks!<br />Mike

 

[Hasbeen]

Re: '91 Mariner 200hp performance / oil leak.

Ill give you my two cents worth, but Im sure you will get more replys!<br /><br />1. sounds like your a little over propped, at least one pitch. You never mentioned what RPM you were turning at WOT and if you were fully trimmed out! This motor should turn 5800 at WOT fully trimmed! Find out what pitch you have, (should be staped on the prop somewhere near the back ring)! Then drop one pitch! Try finding someone that you can borrow one from! Boat shops will sometimes let you borrow one from them with a deposit! I think that will solve a lot of your problems! Did you buy the boat close to the same elevation that you live? If you are higher buy 1000' or more you will have to reprop or rejet!<br /><br />2. Make sure you have fresh fuel, this will make motor idle rough and effect performance! If he only used it once in that amount of time them the fuel is probably stale! good chance you will have to rebuild your carbs after setting that long!<br /><br />3. These V 6s do not idle very smooth anyway, and the smoke after starup is normal! I think they sound great at an idle, but some dont! If you can slowly push the throtle forward and have smooth acceleration then your carbs are probably clean!<br /><br />4. Bass boats set low in the back due to the heavy motor, batteries, and fuel tanks all in the back! Probably not a problem! A jack plate would not likely improve your hole shot, more that likely work against you if you are over propped already!<br /><br />5. Not sure about the oil leak, good question for someone else!<br /><br />6. I think 18 MPH is about as slow as this boat is going to plane, thats about where my 18' (glass) Tracker with a 150 on it falls off! You could buy a Hydrofoil type wing to put on the lower unit which will help some! Also will help get you on plain quicker! Had a boat once that was slow to plain and tried one and they work wonders on some boats!<br /><br />Just reread your post and sence you ar new to boats, you may only think you are fully trimmed down, watch the motor next time at the dock and make sure it is! It will squeal when it is done! Some think that it is down all the way when they slow down but that is just the trailering part of the trim, If it is not all the way down the boat will perform exactly like you describe!!<br /><br />Congradulations on your boat, sounds like a nice one!!<br /><br />Hasbeen

 

[RatherBFishing]

Re: '91 Mariner 200hp performance / oil leak.

Thanks for the input!<br /><br />I just went out and looked and I could find no markings on the prop other than "QuickSilver Lazer II" I didn't pull the prop off the boat though so I really don't know if there may be a stamping somewhere I cant see.<br /><br />I wasn't sure what the max rpms on this motor were so I was concerned about over reving it. I think I was running a little over 5000 rpms when I had it to the top speed I was going, but I didn't have the throttle all the way forward for fear of over reving. The tach only goes up to 6000 so I figured the max was somewhere less than that.

 

[The Marine Doctor]

Re: '91 Mariner 200hp performance / oil leak.

Your oil leak will most likely be the shifter shaft seal.<br /><br />TMD

 

[RatherBFishing]

Re: '91 Mariner 200hp performance / oil leak.

Shifter shaft seal. How hard is that to replace? I am somewhat mechanically inclined. I like to do as much as I can on my own. Can you recommend a good shop manual for this engine?<br /><br />Thanks!

 

[RatherBFishing]

Re: '91 Mariner 200hp performance / oil leak.

Well I had the boat out again this weekend. Was fishing a tournament so I really didn't have time to play, but I did let the rpms go up a bit more. I pretty much had it at WOT (I assume that meand wide open throttle) and it did give me about 63mph (Per the speedo, didn't think of looking at the gps) at about 5800 rpms per the tach. That was with 2 people, full fishing gear and rear tank full and mid tank about 1/4. Unfortunately there weren't any fish in the livewell to add to the weight <br /><br />It seemed to get up on plane a lot quicker. I eased the throttle forward rather than just flooring it. Does it work like a car and if you give it too much gas it spins the tires (or in this case cavitates the prop)?

 

[Hasbeen]

Re: '91 Mariner 200hp performance / oil leak.

Sounds like the boat is performing right in the ball park for the setup you are running! I think that there is probably a little more to be had, but you would more than likely spend $1000.00 to get another 3-5 MPH! Raise the motor, jack plate etc. If you have time and money to burn then thats an option! I do not know if your prop is vented or not? (Holes drilled at the leading edge of the blades in the hub! Very tricky to do it yourself and get it right! If not, that can take care of your cavitation problems at WOT as you come out of the hole! Stiletto four blade props work very well and are vented! About $350.00 at Overtons! I have a five blade vented prop (unknown manufacturer) which performs awesome and it throws a beautiful roostertail!!<br /><br />Sorry the livewells were not full!!<br /><br />Hasbeen

 

[RatherBFishing]

Re: '91 Mariner 200hp performance / oil leak.

The prop is vented I guess. It has a square hole in front of each of the 3 blades. One of the vents though has a plastic cover or plug in it. Should I pull that out?<br /><br />My dad suggestted a 4 blade prop. I may do that when I get some money saved up. I don't get any rooster tail at all with this one. <br /><br />Thanks,<br />Mike

 

[The Marine Doctor]

Re: '91 Mariner 200hp performance / oil leak.

To repair the oil leak you will need a special tool to remove the shifter bushing.<br />This is someething you can do yourself..the tool is cheap enough and it will cost less to do it yourself rather than a repair shop.<br /><br />TMD

 

[Hasbeen]

Re: '91 Mariner 200hp performance / oil leak.

Im not familiar with that prop although I know there are a lot of them out there. I am asuming that the plugs were there so if you didnt like the performance with the vents you could put the plugs back in! Because the other ones are gone, I would take the other one out as it could imbalance things. If you are able to trim out all the way without blow out, then your motor could stand to be raised at least one hole on the transom! There is a point at which you can get too high and the water inlet will actually come out of the water, I do not think that one more hole would approch that though! Its a big job, take the best part of a day, usually have to pull the tank unless you can get behind it to get at the bottom two bolts! Would probably add as much as 3-5 MPH. That, with a five blade prop might get you to the 70 MPH mark! Its just up to you if you want to take the time to do it, sometimes its just fun to see how much performance you can squeeze out of you boat!<br />I personally use synthetics all through my Merc 150. Lower unit, and oil, This alone will give you 300 to 500 more RPMs at the top end. Ams/oil, Synergyn, Penzoil! I use Synergyn, ( Ya Ive seen the post on Synergyn, but its bunk! If it blows up it must be the oil, right??) Sometimes enough to go to the next pitch prop! Transfers to another couple MPH!<br /><br />Have fun!!<br /><br />Hasbeen

 

[RatherBFishing]

Re: '91 Mariner 200hp performance / oil leak.

Thanks Hasbeen and Marine Doctor. I got the repair done over the winter and finally got it in the water a couple weeks ago. I still have my cavitation issue as expected, but the oil leak seems to be resolved. All went well with the repair except for a new water pump case was required since I was following the torque specs on the nuts and found that 50 ft lbs was too much for a plastic case. I will take that one up with the Clymer publisher. <br /><br />As I understand, the tube on my 24p Lazer II prop is too small causing my cavitation issues. Now I need to figure out what prop to buy. I have a line on a used 24p High Five prop. Assuming that has the right sized tube, I may give that a try.<br /><br />Thanks guys!<br />Mike

 

[wilde1j]

Re: '91 Mariner 200hp performance / oil leak.

Maybe it read 50 in-lbs? BIG difference!

 

[RatherBFishing]

Re: '91 Mariner 200hp performance / oil leak.

Doh!!! Jim, you are correct! It does read 50 in-lbs. I assume my torque wrench is ft lbs. My appologies to the Clymer people. I never realized there was two different measurments used.

 

[RatherBFishing]

Re: '91 Mariner 200hp performance / oil leak.

Update - Repairs seem to be holding. No oil leak. Seems to pump water just fine. The speedo does not work but I had replaced the tube while I was in there and the new one is more flexible than the old and I suspect it is pinched or I didn't route it right. I have gps so is not a big issue.<br /><br />I picked up a 24p 4 blade trophy and it seems to have solved my ventilation issue. Actually, I suspect the issue was more the thrust washer that was on the old one. The one that came with the new prop is a lot less diameter. I suspect the old one may have restricted my exhaust a lot. Anyway, the thing jumps up on plane with no problem and I am getting almost 60mph fully loaded with fishing gear and 2 people. <br /><br />The thing still idles really rough and smokes a lot at idle, but seems to run well past 1000 rpms. <br /><br />Thanks to all for your advice!