mechanic says forget about it!!!!!

i've posted before and got some answers but now i am scared we got screwed. have a 17 ft renkin open bow with 2.5 merc and 3.0 carb. compression on 2 end cylinders were 150 and the other two were 125.<br /><br />replaced rusty plugs and changed points. adjusted the timing by 8 degrees. now going out to test it on the water also with a 17 inch prop instead of the 19 it came with.<br /><br />we did this work as rpms were really low and took forever with 2 adults to get out of the hole and barely got up on step with 5 adults. this is supposed to be our ski boat. rpms were 3500 with 2...and about 3800 with 5. no speedometre on board. book says our type of engine should run at 4800.<br /><br />is there something else we should look for if this test drive is still a bust...after the above work being done. our mechanic says, save your money and put it in the classifieds. REALLY!! so many of you out here have fixed so much stuff....is our compression really that bad that it is hopeless without a rebuild (was rebuilt by 1st owner and we are 3rd owner)what should our next step be?? sorry this is so long winded..just really frustrated! husband also noticed some "blow by" when testing the boat in a barrel after the above work was done.<br /><br />anya nd all help is much appreciated!!

Re: mechanic says forget about it!!!!!

I dont feel Compression Numbers look all that bad In my Opinion. You would maybe notice a Little rough Idle to it, But the loss of that 25psi Compression is really not going to be felt badly. It would take numbers Lower than that to make a huge difference. What is your Complaint with it ? and Just understand that I find most Techs really dont perform Accurate Comprssion Testing. You must Block throttle wide open, do it on a warm engine, remove all plugs and Count number of revolutions of the engine when doing the test. Most techs spin the motor and get the Highest Numbers, That a False Test. Example to this is doing a Test and having the tech accidently spin and Xtra Revolution, It could mean the difference Between 150 and 125 EASILY !!<br /><br />How does your husband see Blowby ? Explain what he is looking at for me ? and please explain the Original Complaint if you would.

Re: mechanic says forget about it!!!!!

I don't know what the comps should be, but a friend and I just worked on his r22 toyota engine in a pickup and all the cylinders were at 170-175 except for no 3 which was at 125, it had enough blo-by to use a quart of oil in 50 miles. found out that the second comp ring was broken in 2 places, thats 3 pieces! just a thought........

Re: mechanic says forget about it!!!!!

I have the same engine and similar compression numbers (two cylinders in the front 150 and less on the two in the back). My boat has great hole shot and can easily pull a skier with the 17" pitch prop.<br /><br />If it still doesn't do it, check you engine timing. ( I did my timing by "ear" while the boat was running. I know it isn't the best way, but for some reason since I installed my Pertronix electronic ignition, it won't time with the timing light.)<br /><br />Next thing, make sure it is trimmed right (Do you have Power trim? If so trim it all the way in for start up.<br /><br />You can also install a hydrofoil and it will plane in 1/3 the time. I have the Stingray and it works great.<br /><br /> http://www.iboats.com/products/7/21504_stingray_speed_xp_hydrofoil_stabilizer.html

Re: mechanic says forget about it!!!!!

wow thanks everyone. lots of good problem solvers out there.<br /><br />with respect to what's our problem. it's the low rpms and not getting out of the hole and taking a while to get on plane. for rpms see original post. <br /><br />with respect to the blow by..<br />here's what my husband thought-He also said that there is lots of blow by, and the problem could be a heaD gasket...however, you dont know until it is taken apart. The problem could be more serious, such as a complete rebuild. ANY THING TO ADD TO THAT?<br /><br />HERE'S WHAT ELSE HE SAID (the mechanic)<br />He wasnt sure on the condensor in the dist and he did not do a recheck once<br />he reset the timing so im not sure. He did suggest to switch to electronic<br />ignition distributor....<br /><br />if there are any other comments out there..would love to hear them. hoping it's just the prop gut if not working on plan A,B andC...wanna get in the water!!! canadian summers are short enough!!

Re: mechanic says forget about it!!!!!

I Don't see anything tooo far out w/ the compression. That the timing was adjusted 8 degrees does concern my thinking though.... Why? keeps going through it, my head. <br />I would perform a compression test MYSELF, and check the FULL ignition advance, don't know what the specs are for your craft, but wouldn't be suprised to see 30+ degrees or so. I am not sure if I have ever experienced blow by caused by a head gasket, but I don't think so. A vaccum gauge attached would give you some insight as to the internals of this engine. There is alot of advice here about vaccum gauges and how to use them.<br />Seems you would get a better hole shot w/ the different prop. mine did, but experienced cavitation when I turned. <br />Do you think that husband just wants to rebuild this or trade it in?? and the thought just won't go away?<br />Fuel is expensive. I wish I had a four cylinder instead of a V8. We don't ski anymore. speed does co$t. <br />The tools to check these 'tune-up' items aren't expensive. and with a little studying you could do this yourself. I owned an automotive shop in the 70's. Did all of my own work, still do when I can. I birddog mechanics when they work on my cars and trucks. 2 days ago, when I had my oil changed, the mechanic forgot to put on the new oil filter! usally they just forget to tighten the drain plug. I let him lower the truck and slide the lift out of the way before I asked him if a filter was included in the price or if it was extra. get a second opinion on what you have, or do it yourself. Post your findings...sl

Re: mechanic says forget about it!!!!!

Get youself the Pertronix ignition. It is a module you install in your existing distributor. I bought the Pertronix II for mine and it protects you in case you left the key on "on" in the ignition (vs. the regular Pertronix that doesn't and can break down.)<br /><br />You can also get the Pertronix II coil to go with it, but it also requires non copper core wiring. It is supposed to give you some extra power, but I couldn't tell the difference. I'd just buy the module and leave the existing coil and wiring for now. My engine is far smoother with this conversion. My points and condensor worked fine<br />before... I just wanted to get away from adjusting the points and dwell.<br /><br /><br /> http://www.pertronix.com/ <br /><br />I bought it here:<br /><br /> http://www.vintageperformance.com/retrorockets/index.htm <br /><br />You will need this one:<br />91146A <br /><br />found here:<br /><br /><br /> http://www.vintageperformance.com/retrorockets/johnson-.htm <br /><br />...also use 89 octane fuel (mid grade)

Re: mechanic says forget about it!!!!!

The 2.5 is the 120 hp engine. I'm surprised it even got up on plane with five adults. The Mercruiser manual calls for the 120 in a 15-17 foot boat to rev between 3900-4300 rpms with a 15x23 alum prop. SS prop would be 13.5x23. A 16-18 foot boat would need 15 1/4x 21 prop. Be sure you have the correct outdrive on the boat. It should have a 1.98:1 drive.

Re: mechanic says forget about it!!!!!

Keltie,Hope you have found the motor to be running okay.I just have to question your part about rusted sparkplugs.<br />Can you tell me more?Where was the rust?<br /><br />DHP

Re: mechanic says forget about it!!!!!

lets start with the basics<br />1. my boat is a maxium 2000sc weights about 2800#<br />it has 3.0 xl merc which is a 130 hp motor<br />2. i am able to do everything you seam to want to do with littel problem so i think you should be able to do what you want<br />3.i havent read anything about the condition of your bottom but that can make or break the whole thing <br />is the bottom clean even if it is a bunch of old coats of paint make for a very slow boat compared to clean bare fiberglass let us know about the bottom<br />4.my last boat was a 16 ft sportcraft bow rider and that boat had more paces to hide water than you could believe easy to have 40 or more gallons that did not make it to the bilgepump<br />tommays

Re: mechanic says forget about it!!!!!

I had a boat problem similar at one time. It had the OMC 3.0 liter. It got where it would not plane out with a small load in it. I checked the engine through and through and found nothing bad wrong with it. Then noticed that the transom was filled full of rot and soggy wood. Infact just about the half the boat was. I imagine the boat weighed much more than it did when it was dry. I hope this is not your problem. Good luck

Re: mechanic says forget about it!!!!!

do the points have the proper dwell? hows the carb? fuel filter pluged? fuel tank vent clear? carbon on top of the pistons? throttle adjusted properly? check the easy stuff your self, and mabe find a mechanic that will work with you not write you off.

Re: mechanic says forget about it!!!!!

I am surprised the mechanic did not replace the condensor, they're so inexpensive comparatively. As you mentioned, Canadian summers are very short, concentrate on getting in the water fast and doing overhauls in the Fall/WInter. <br /><br />1 - Compression is reasonable, given normal long-term wear. No back fires, water in the oil?<br />2 - Replace the condensor, set dwell and timing to spec, adjust carb (if you're able), also replace distributor cap and rotor.<br />3 - Put on the 17 pitch prop.<br />4 - The electronic ignition will help immensely, but it will not make a worn or mechanically trouble engine, new.<br />5 - If you see improvement and are satisfied that the prop and new ignition parts may do the job, consider new plug wires also.<br /><br />I think this could provide short-term fun for under $100.

Re: mechanic says forget about it!!!!!

I have the same 2.5 engine in a blue water 16.5 foot boat. I'm not sure if it's the right combo but I have a 14.5X17 prop and I can hole shot my 240lb friend out of the water with 4 other people on the boat. BUT! I top out at 32mph @ 4300rpm. Sacrafice what you don't need. For me 32mph is more than good as long as I can wakeboard.

Re: mechanic says forget about it!!!!!

wow thanks everyone. just got back from calgary for a family visit and read all your posts. apparantly my husband went out with the new 17 inch prop and noticed a difference. now get up to 4200-4300 rpms. thought that was pretty good.<br />also bought a hydrofoil and installed that. we are going out tonight for the august long weekend to give it a go and see if that makes it any better.<br />thanx to all of you who replied. look forward to reading any other ideas that will help us bump up the boats performance

Re: mechanic says forget about it!!!!!

Hey, what long weekend??????

Re: mechanic says forget about it!!!!!

I have a 120 on 16' 4winns. WOT is 4800, 34mph. Now that the carb is rebuilt, hole shot is much better. Have SS prop of unknown pitch.

Re: mechanic says forget about it!!!!!

Up here in Ontario Steve we get civic holiday for August 1 or the first monday of August... hey we can't wait until labour day it could be snowing by then. I should be at the cottage and in the boat by 09:00hrs. Hope you had a good long weekend keltie.

Re: mechanic says forget about it!!!!!

Keltie, I havent had a chance to get back to this but I read all the other responses after My post and as always they have lots of Good ideas !<br /><br />First, How is the boat going ? <br />Second, Like someone else said, Why didnt this mechanic just change out the Condenser if he thought it was that ? I also would not Invest in electronic Ignition untill I knew 100% what the engine problems are, or could be...Points work fine when they are Installed and Adjusted Correctly.<br /><br />Third: The Blowby and Rusty plugs also still have me wondering.

Re: mechanic says forget about it!!!!!

Steve H. regarding "long August" w/e. Do you Realize That In Canada, (and most other places), that they don't have a long July 4th weekend??..sl <br /><br /> "ONLY IN AMERICA"