Another not reaching max rpm post.

mklearl

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Apr 21, 2013
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How is the "Hole Shot" on this boat? From what I read in the posts, it appears to me to be over propped and may also be a tach issue. This boat is a 28 footer at 7500 pounds with a single 5.0 pushing a 1.95 out drive with D4 props, Would expect D1 or D2s on this. 35 mph isn't bad for a boat of this size and weight on a single 5.0. If it's able to get up on plane and doesn't struggle, I would look at the back of your tach and see that it's set for a V-8. There's an adjustment screw to set for a 4 cyl, 6 cyl, then 8. Won't read correctly if it's not right. D4 to me is big prop for that boat and the 1.95 outdrive. Would seem more likely on the 2.30 DPS.

I'll check on the tach. I can't really tell you about the hole shot as I can't really shoot it up to full throttle. 3600 rpms that's when it gets on plane and properly trimmed. I'd say sluggish to say the least but I have nothing to compare it to. As far as the props are concerned they are the original props. That motor and drive were professionally installed in the hull. Used boat but brand new motor. I seriously doubt that the po ran around for 432 hours with it missing 1000-1400 rpms and thought "good enough."
I do wish it had the 5.7 in it, but I also think there is a performance issue.
These hulls were mass produced and we're built for tuna fishing with for the religious cult "moonies" led by reverend moon. They are long and built heavy but are one of the first true deep v boats built. The boats were mostly equipped with 235 2 stroke outboards. I think the 5.0gi with the dp is comparable if not superior.
I will however check all suggestions! Like I said, I have nothing to compare it to and I'm learning along the way.
Thanks again
 

ericga

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Mar 4, 2012
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Is that Dexter Morgan with the yellow shirt in the picture? :)
 

Fishhead-1

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I'm thinking props also ,my boat same weight and ratio with a 5.7 and am running f3 which are lower than yours
 

mklearl

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Apr 21, 2013
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The motor was purchased brand new and installed professionally. I don't know how they determine which props to put on but I'm sure there is a formula they use. I'm sure the installer chose the props and I can't believe that they as well as the previous owner (my deceased father) were ok with it only getting 3600 rpms wot. When I inherited the boat there were 2 sets of D4 props. Short of shelling out $1000 for a new set of props to "try out" how do I determine what the correct props are?


I'm thinking props also ,my boat same weight and ratio with a 5.7 and am running f3 which are lower than yours

Does your boat also have a 60 degree bow angle, 22 at the stern and only an 8 ft beam? I'm not ruling out the props... I just can't believe he and the installers were ok with a brand new motor running like that. I also am not sure how to rule that out.
Knock senso ordered, I'll do a vacuum test and possibly a leak down test. Then go from there. Thanks again for all the suggestions and help.
 
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Fishhead-1

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Oct 10, 2003
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I'm 22 degree also on a 24 footer. Be careful because those vortecs can and will tulip intake valves if they are overproped and lugged. Ask me how I know that. Good luck
 

mklearl

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Apr 21, 2013
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I'm 22 degree also on a 24 footer. Be careful because those vortecs can and will tulip intake valves if they are overproped and lugged. Ask me how I know that. Good luck

I was more referring to the 62 degree bow entry and making a point that although weights and power being similar there is a big difference between pushing a bayliner through the water and pushing a deep v hull. I get your point and understand your concern but being a setup that was professionally installed and has been that way for the previous 400+ hours leads me to believe that the problem is mechanical which I will troubleshoot first. I'm sure I could put some d3s or 2s or even d1s on the motor until I reach 5000 rpms. That doesn't mean that there isn't an engine problem... just means that there is less of a load on the props allowing the engine, faulty or not, to increase rpms. So again my question remains... if everything looks good mechanically how do I determine what the best prop set is other than shelling out $1k?
I will say this though... on the prop chart from volvo the d4s aren't even listed for my engine... it's d3s or lower. On the other hand the f series props the recommendation is f4 and higjer...However the chart is based on what the potential speed of your boat is. Well how am I supposed to know the specific potential speed of my boat if I don't know what prop I'm supposed to put on? *** backwards in mho. I'll try to post the chart. I have a 5.0gipbycce with a dpsm 1.95 outdrive.
 
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mklearl

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ericga

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...So again my question remains... if everything looks good mechanically how do I determine what the best prop set is other than shelling out $1k?

If you explain you suspect the boat is over prop I'm sure you can find a place willing to offer a "try before you buy". Smaller marinas or specialized prop shops are usually more open to this.
 

mklearl

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A couple of notes. I changed out the knock sensor. The old one was in rough shape but there is no difference in performance. Rpms still idle around 500 which is low. The vacuum gauge I tapped into a port on the intake... looking at the schematics I found there was a plug on top of the intake manifold... reads a steady 16. When the throttle is pushed up it drops down to about 10 and then back up to over 20 in the normal range.
During the test I removed the hose from the pvc valve. Rpms increased to an idle of about 1400 rpms and the vacuum gauge read about 21. Is it possible the pcv valve is bad and causing this? With the hose removed I also pushed the throttle up. There was a small hesitation and a slight drop on the vacuum gauge but not nearly as bad.
Thanks again
 

alldodge

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I'm late coming in but came from your other vacuum thread.
It's not the PVC valve and the vacuum readings your getting are what you should see, don't see an issue.

My 27 cent review:

To see if its the knock sensor just take the wire off. I don't think your ECM has a code 44 sort of thing which will retard timing being it is a VST and in the MEFI-1 arena.

Previous post said your getting 180 psi across the board. This one I have issues with for two reasons.
1) The readings are to high for a straight 5.0, not to mention one that sat for 10 years.
2) No engine has perfect compression across the board +/- 5 psi except when new

From what I can find the 1998 28 foot master marine weights in around 4600 for I/O and OB. Having an I/O I would add another 1200, then gear which will put you in the 6000 +/- 200. The weight isn't the major call, but just trying to get a perspective. While the boat does have a blunt nose it doesn't draft much water. With Max HP at 350 I don't see any issue why the boat will not perform.

The boat has been in the family for a long time and the props were original is what I'm reading.

Fuel pressure is good for the 5.0 from the chart provided. It stays at 30 psi when running WOT. At WOT if the IAC is also wide open this will have no effect on max rpm. The IAC has impact on idle and lower rpm, can also cause hesitation.

It's my understanding that you don't know how fast the boat would run at WOT prior to receiving it. It could very well be that the original props were chosen under the pretense that they would get better fuel economy, I have no idea. If I knew what pitch a D4 prop was I could see what kind of prop slip there is.

Need to know what pitch is a D4
Would like to see what codes if any are showing up
Would like the compression test redone with a different gauge to verify results
Would like to see what a leak down test shows.
Also not 100% sure your Tach is correct
 

mklearl

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I'm late coming in but came from your other vacuum thread.
It's not the PVC valve and the vacuum readings your getting are what you should see, don't see an issue.

My 27 cent review:

To see if its the knock sensor just take the wire off. I don't think your ECM has a code 44 sort of thing which will retard timing being it is a VST and in the MEFI-1 arena.

Previous post said your getting 180 psi across the board. This one I have issues with for two reasons.
1) The readings are to high for a straight 5.0, not to mention one that sat for 10 years.
2) No engine has perfect compression across the board +/- 5 psi except when new

From what I can find the 1998 28 foot master marine weights in around 4600 for I/O and OB. Having an I/O I would add another 1200, then gear which will put you in the 6000 +/- 200. The weight isn't the major call, but just trying to get a perspective. While the boat does have a blunt nose it doesn't draft much water. With Max HP at 350 I don't see any issue why the boat will not perform.

The boat has been in the family for a long time and the props were original is what I'm reading.

Fuel pressure is good for the 5.0 from the chart provided. It stays at 30 psi when running WOT. At WOT if the IAC is also wide open this will have no effect on max rpm. The IAC has impact on idle and lower rpm, can also cause hesitation.

It's my understanding that you don't know how fast the boat would run at WOT prior to receiving it. It could very well be that the original props were chosen under the pretense that they would get better fuel economy, I have no idea. If I knew what pitch a D4 prop was I could see what kind of prop slip there is.

Need to know what pitch is a D4
Would like to see what codes if any are showing up
Would like the compression test redone with a different gauge to verify results
Would like to see what a leak down test shows.
Also not 100% sure your Tach is correct

You are not late to the party and I appreciate all the help. I'm determined to get this running right and I will... I promise.
Couple of points... when doing the compression test I was expecting a large discrepancy... so yes. .. 180 across the boarday not be true... but 175 to 185 is a conservative discrepancy to the test... 10 psi is well within range. But as stated... I will redo the test just as I rechecked the timing today.
Second... I will not chase a prop issue until the engine problem is resolved... which I think there is.
Third... there is a definately low vacuum at idle. I have read different posts on how to read the vacuum gauge as well as read the manual... my engine has multiple scenarios. So I don't know which way to go.
I think that my next step is a leakdown test. I have replaced the knock sensor today with no change
I don't have a code reader so I'm flying by night. Winterizing tomorrow so it looks like leakdown test over the winter and go from there.
 

mklearl

Petty Officer 1st Class
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Apr 21, 2013
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Specs http://boatspecs.iboats.com/Master_Marine__TE-284_Good_Go__1998/bp/66b169925

Compression for a 5.0 or 5.7 should be in the 150 range, your way to high

Not asking to chase a prop issue, I asked what pitch is the D4 series prop

Sorry... many have suggested over propped. In terms of compression... the manual gives a compression pressure limit chart from a min of 102 to a max of 212 assuming that the lowest reading number is at least 75% of the highest reading. I think I fall well within that criteria.
 
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