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| PD Power loss... HELP!! http://www.mudmotortalk.com/mmt_v2/viewtopic.php?f=3&t=73116 |
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| Author: | mguthr1 [ Mon Oct 15, 2018 3:36 pm ] |
| Post subject: | PD Power loss... HELP!! |
Boat was running 33-34 unloaded, 31 with a load. It sat for about 5 months but I ran it in the garage every week for a couple minutes. Ran it to go fishing yesterday and couldn't get it over 25 mph. Replaced fuel lines, replaced old fuel and cleaned carb today. Ran it and still only gettig 25-26mph. Rented a compression tester and getting 140psi on one side and 95psi on the other. What the hell happened over night? Not understanding how this happened but need to find a remedy. It has Peltier 310 cam, mikuni, MAC Baffled (this was the only change in that timeframe from a MAC unbaffled) and heads are decked. Is it the heads or rings and what is the best way to get this engine running strong again. Another thing is it starts VERY weak... like an old man coughing weak. It has very little power and takes a while to get to full rpms on the water. Thanks for the help. |
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| Author: | Russ [ Mon Oct 15, 2018 4:44 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Check your valve lash. Should be a regular maintenance thing anyway. #CFFITR #TheGhostBoat #whoneedsphysicsihaveamudmotor |
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| Author: | mguthr1 [ Mon Oct 15, 2018 4:57 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Forgot to add, checked valve lash and all is good. |
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| Author: | Will C [ Mon Oct 15, 2018 5:08 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Leakdown test. If your that low on compression u need to find out why asap. A popped headgasket will cut the top surface of the block if not caught quickly |
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| Author: | mguthr1 [ Mon Oct 15, 2018 5:48 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Also changed plugs and one side is running richer than the other... can someone explain that? |
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| Author: | mguthr1 [ Mon Oct 15, 2018 5:49 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
The 90psi side for reference is running richer than the other side. |
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| Author: | dead animal [ Mon Oct 15, 2018 6:08 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
just to let u know.... if u got 140 on one side and 90 on d other. the side with 90 has a problem. if it's over your head go get it checked out. running the motor like that is not good for it. good luck! |
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| Author: | mguthr1 [ Mon Oct 15, 2018 7:45 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Yea so I just checked the compression today and found out, so the motor will not be run until fixed. Appreciate the heads up.... I am just curious about the leakdown and what is my next move. I don’t want to throw a ton of money at this thing, just really want to get it back running stron and dependable. |
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| Author: | Will C [ Mon Oct 15, 2018 9:57 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
| Author: | Will C [ Mon Oct 15, 2018 10:02 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
As a freebie check you can look about 1/2 way down the pushrods for a line on them. When a gasket is popped it sometimes leaves a mark on pushrods near where the head meets the block |
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| Author: | OwenDickeson [ Tue Oct 16, 2018 10:46 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
Blown head gasket and not doing compression test with the throttle wide open. That's my guess. If you have access to a leakdown tester, you can pull the push rods out and pressurize the cylinder with the low compression and see if air is coming out inbetween the head and block where the push rods are. |
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| Author: | mguthr1 [ Wed Oct 17, 2018 8:27 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
I ordered a leakdown tester and will be doing it tomorrow. I also ordered new gaskets and hope that is all it is. Shouldnt my compression test show ~145-150psi with the heads decked .05 at least on the good side?? |
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| Author: | mguthr1 [ Wed Oct 17, 2018 12:41 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Just pulled the heads, gaskets we’re good. No signs of leakage. |
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| Author: | mguthr1 [ Wed Oct 17, 2018 12:48 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Also sprayed some wd-40 in the intake and exhaust inlets to see if there was any leakage by the valves. The 90psi side had seepage past the valve on the intake side. Would this be causing that much power loss?? And I am guessing this is my issue since the head gaskets we’re good still..... |
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| Author: | Will C [ Wed Oct 17, 2018 2:03 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
For compression to be down to 90 it's not likely from a seaping valve. Now if you hold head up to light and can see a daylight around the intake valve then maybe. Like Owen said, did u do compression test with throttle wide open? Also put a pushrod onto each lifter and make sure you have full cam lobe travel |
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| Author: | mguthr1 [ Wed Oct 17, 2018 3:52 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
So heads are being machined at the moment around the valves and a small Amon t decked off again. Should I replace rings while down?? Only thing left would be the cam if it still is not running a full capacity. |
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| Author: | mguthr1 [ Wed Oct 17, 2018 4:02 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Also would a leaking intake valve create a “long start” situation? Like it cranks but takes a while until it gains momentum to keep going... like a very weak motor.. like exhaust gas is being pushed into the intake... |
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| Author: | Russ [ Wed Oct 17, 2018 7:55 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Did you do a leakdown test before you started having stuff machined? #CFFITR #TheGhostBoat #whoneedsphysicsihaveamudmotor |
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| Author: | Will C [ Wed Oct 17, 2018 8:31 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Dam man you just jumped right in, lol. As far as rings go I would look at the condition of the cross hatch in cylinder. If the cylinder caused it you would likely be able to see it. Also noticed you have a peltier cam. That is probably billet and highly unlikely that It's a flat lobe. Check it anyway and do the leakdown when your heads come back. Do the leakdown before installing the pushrods |
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| Author: | mguthr1 [ Thu Oct 18, 2018 10:14 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
Will do, and yea kind of jumped the gun. I cant stand waiting on things and I need it to be right so I do not get stranded. I had a suspicion it was the valves due to the crappy long winded start it does... |
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| Author: | Russ [ Thu Oct 18, 2018 12:06 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
You want it to be right, but you didn't even figure out the ultimate problem before the metal cutting started. You're still guessing at this point as to whether or not that'll fix the issue. #CFFITR #TheGhostBoat #whoneedsphysicsihaveamudmotor |
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| Author: | dead animal [ Thu Oct 18, 2018 3:32 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
go buy u a stock 40 briggs and run it on u pd. that way u can have a reliable stock motor and a hopped up pos for when you need to go 2 mph faster. best of luck with your situation. |
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| Author: | Russ [ Thu Oct 18, 2018 3:58 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
| Author: | Wchauvin [ Thu Oct 18, 2018 6:52 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
I don't know, I have a similar motor. I have over 2000 hours on a 23 gdlt, galvanized frame that runs like a top. Just changed the head cover gaskets yesterday and went through it before season for my back up boat. I hope I get over 5k on it as well lol |
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| Author: | dead animal [ Fri Oct 19, 2018 5:59 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
ain't that the truth! they are all pos's!! lol u just never know when they will go boom. |
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| Author: | Bigen [ Sat Oct 20, 2018 9:51 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
| Author: | mguthr1 [ Mon Oct 29, 2018 8:44 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
So I put everything back together after the valves were redone and with a leakdown I had a supply pressure of 100psi and leak of 98psi on both. They are seated almost perfectly and I feel confident with them. The other issue is that I only go 27mph vs the 25-26 last time when the valves were leaking. Keep in mind that the only change from running 33-34 a couple months ago till now is a MAC Baffled exhaust. I had the unbaffled on when it was running good. Could the restricted flow of a baffled exhaust cause a 5-6mph difference??? I have not checked the cam yet as I dont want to pull the case gasket yet. I am stuck on non free flowing exhaust being the smoking gun.. Thats the only change that has happened since the slower speeds and loss of power. Thanks in advance. |
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| Author: | banded-mallard [ Mon Oct 29, 2018 9:12 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
| Author: | Will C [ Mon Oct 29, 2018 10:02 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
Extra bump in bottom of boat happens a lot in my neighborhood |
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| Author: | mguthr1 [ Mon Oct 29, 2018 10:16 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
| Author: | OwenDickeson [ Mon Oct 29, 2018 1:09 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
It's not the exhaust. |
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| Author: | mguthr1 [ Thu Nov 01, 2018 12:28 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
| Author: | 270Handiman [ Thu Nov 01, 2018 8:52 pm ] |
| Post subject: | Re: PD Power loss... HELP!! |
Do you still have a 50 psi difference in cranking compression between the two cylinders? Sent from my SM-G965U using Tapatalk |
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| Author: | mguthr1 [ Fri Nov 02, 2018 6:38 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
Just for clarification, the heads were redecked and I am using copper gaskets now (same thickness as the new decking job). The valve seats were re-cut to insure proper seal and now had a good leakage test on both cylinders. Now for the results.... I put an Unbaffled MAC dual outlet on yesterday and ran 33mph again. SO, for anyone that says exhaust will not cause an issue like that, there is your answer. By simply changing the exhaust, i lost anywhere from 6-7mph going to a more restrictive design. |
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| Author: | OwenDickeson [ Fri Nov 02, 2018 8:09 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
| Author: | caddobrook [ Fri Nov 02, 2018 9:19 am ] |
| Post subject: | Re: PD Power loss... HELP!! |
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