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Bad Vibration and engine blow by

bountyhunter

bountyhunter

Member
Finally got to take her out yesterday, 1976 Checkmate Jetmate 455 Olds w/ Jacuzzi pump. Had a little problem starting but got it started. Let it idle for a few minutes, then headed out of the no-wake zone. Oil pressure right at 50, Temp was around 190, gave it some gas and temp went down to 180, but then :confused: the whole boat began to vibrate really bad and made a noise like a bearing in the pump was going bad. A friend that was with me thought it was the engine, but as we went across so small wakes the noise would come and go. As I gave it more throttle the noise would do the same quit and start. Then we noticed smoke coming out of the left side exhaust and the breather cap on the valve cover (left side) and a straight stream of smoke coming from the back of the intake manifold, then the oil pressure went to right at 0. Idled it down and for a couple of minutes and pressure came back up to around 35-40. No engine knocks or pings or anything that indicated it no getting oil. After pressure came back up, gave it some more gas and as we started to move the pressure dropped again top 0, stayed there all the way back to dock. When I bought the boat I was worried about it having a cracked block, but check oil after we got back and no water in it. All of the gauges are new, could it be the wiring. Have to go for now. Would appreciate any suggestions.
Thanks
 
smoke or stream??? you my have a cracked head or gasket
??? its allowing water into the cylider..and it's steaming it off......as far as your oil problem it sounds like it maybe a bad cam bearing
 
Thanks Hot,
It's actually smoke from the cap on the valve cover and you can smell the oil when it gets on the engine, you know how oil smells if you pour some in your engine and spill some on hot exhaust. I found some oil on the back of the engine close to the distributor and it looks like it's coming from the back of the intake manifold where it looks like gasket sealer or gasket maybe gone. My friend said his Jetski had a rel bad vibration in it and had no power. He took it to his mechanic and they found one of those plastic 6 pack bottle carriers as jammed in the impeller, once they got that out it ran like it was suppose too. So I got my jet pump manual out and read the trouble shooting part and it said some debris maybe in the pump, so that's my next step.
 
Engine doesn't smoke while idling, only when trying to get up some speed. if it had a cracked head or gasket wouldn't it get hotter than 190? The engine does fine at idle and just above idle. It's higher RPMS that does it in.
Does anybody know where to buy some parts for my Jacuzzi pump, if I need them?
Thanks
 
no MOST of the water is keeping it Kool but some maybe leaking past the gasket I would pull the top half ...iintake beacause it's leaking oil the head to inspect them gaskets are cheap and you can check for cylinder wear ......... if you take the heads off flip them up side down filleach hole with gas and fuel that leaks out wil leave a trail and an empty hole ..it's cheap and easy.....you'll have a saturday afternoon into it maybe $100 an you will kknow whats going on...you could alos do a leak down test pull the valve covers pull the rockers off fill it with comp air ( be sure to hold the flywheel )and see if it leaks down this will give you a good idea at which hole to look at
 
Sounds like you have several issues. The vibration can come from several things. Did you grease the pump bearing and u-joints. As far as oil pressure going from 40 to 0 that has nothing to do with a head gasket leaking or bad valves or the engine temp.

I had to read this a couple of times to answer. You said you had good oil pressure at idle. You start to take off and oil pressure drops to 0 then the engine starts smoking. You de-throttle the boat back down to idle and the oil pressure comes back.

Here is what I think might be the problem the oil passages are clogged in the head and will not let the oil drain back to the oil pan fast enough. The results of this is.

Good oil psi at idle
lost of oil psi when throttling up because the oil is trapped on top of the head and can't drain

Smoking because to much oil is going by the valve guides into the cylinders and exhaust from to much oil on top of the head.

From the way you described your problem this is my theory. I have seen tthis happen before.
 
thats a new on on me but at least it will only take a few min to pull the vavle cover off and see...my guess...bad bearings......or your oil filter maybe full of poop and it's trying to use the by pass??? what type of oil are you useing?? weight no brand and when did you last change them???
 
Hottrucks said:
thats a new on on me but at least it will only take a few min to pull the vavle cover off and see...my guess...bad bearings......or your oil filter maybe full of poop and it's trying to use the by pass??? what type of oil are you useing?? weight no brand and when did you last change them???
Click to expand...

If the oil filter was clogged forcing the bypass to open you would not loose all the oil psi and when he throttled up heavy the filter would blow off. If the bearings where shot it would have less oil psi when hot at idle,, and more oil psi when he throttled up. But in his case he has great oil psi at idle and none when on the throttle. The oil pick up could be broke or clogged but that does not explain the smoking.

A sludged up engine that has been sitting around with moisture is what clogs the oil passages I seen this happen on some tired gummy engines
 
HI Big Red,
Thank you. No I did not grease the pump bearing or u-joint, if you remember Red, I just got this boat, where do you grease the pump? The U-joint I know about.
I cranked it again this afternoon (for less than a minute) oil pressure was at 35. A friend of mine that works at a machine shop and rebuilds engines came by today and looked at it, of course the thing wouldn't start, but it did fire off once. He said from what he heard that the main problem is not in the engine, it's somewhere else. I did a compression check on all cyls. Lowest one was 90, 3 at 120, 2 at 110, 1 at 105, 1 at 100. The readings did go up after I squirted some oil in each cyl and checked it agian,
they increased from 15 to 35 lbs. I put the plugs back in it and it started after the 3rd try. My freind says it just needs to be run since it's been sitting. Smoke coming from the back of the Intake Manifold is because the gasket/gasket seaker is gone right there.
I took the inspection plate of the pump like the manual said too, to look for debris in the pump. I didn't find anything in it. Big Red I know you use to own one just like mine, is there an easy way to change the U-Joint and/or bearing or do I have to take the whole pump system off.
Thanks to all of you for all of the help and information.
 
The engine only smoked a little (but quit when idled back down)and only on the left side of the engine and smoke was coming out of the non-vented cap on the left valve cover as well as the back of the intake manifold which figured that one out, because of the gap between the intake and block. The oil and oil filter are new, only ran it a couple of times (less than a minute each time), until we took it out Saturday. Maybe I shouldn't have but when it started this afternoon, I romped down on the pedal a couple of times to see what it would do and it responded immediately and no knocks/pings and only 35 lbs oil pressure, hope I didn't hurt the pump, but then again it may already be bad. When we had it in the water, she would move but had no get up and go the vibration was to bad to try to give it more gas.
 
I had a '79 Youngblood with BB Chevy and dominator pump. I sucked debris up in pump a couple different times, the only way I found the trash was to open hand hole and back boat into water deep enough for water to come out hand hole. Unbolt u-joint from crank first so you can manually spin pump both directions. If there is a stick or something in there this should flush it out. I spent a couple hours late one evening on boat ramp trying to get a stick out. I think Red's logic on the oil pressure is right on. Not big fan of 455 olds engines anyway. If you really want that thing to run put a BB Chevy in it. I had 7k rev limiter on my BB Chevy never had any problems, it would run about 105mph. Rebuilt pump when I rebuilt engine, ran it hard for 5 summers straight, pretty much maintenance free. Footed and skied all the time behind it, awesome boat, loved the dominator pump. Put droop snoot on it, helped a ton on holeshot, and helped keep boat more stable.
 
The grease fitting for the big pump bearing is in the back. Go to the back of the boat and look in the pump where the water comes out. There is a fitting inside their and I believe a fitting on the inside of the engine compartment rite at the back near the transom.

If you have anymore questions about your pump call Tom Morrow he helped me with mine and also sells the J-pump parts. He also knows a Checkmate jetbaot. He is real old school and a good guy.

http://www.jetpumprepair.net/Home_Page.php

FOYBOY I will agree with some. The 455 is a good engine but the reason they stopped using them in hi performance jetboats is because it was to hard to get the rpms out of them. The BB Chevy was easier to build and it stayed together longer at high rpms.

The 455 is a good reliable engine if built right with mild hop ups. But for extreme hp and rpms its no match for the BB Chevy
 
lay under the boat with a light look real carefully thru the intake grate all around the impellor, it only takes a small peice to cause the vibration....had a small(less than 1/2") in my jucuzzi once caused the same issue..on the engine OP, could the oil pump pick up have come off like a chevy ?? not sure on the olds...but does happen on chevys at times..Rob
 
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