Uggh. I may have ruined my rebuilt motor with wrong OIL weight
10-24-2002, 01:21 PM
#1
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Uggh. I may have ruined my rebuilt motor with wrong OIL weight
Hey guys,
I just finished the 20HR breakin on my rebuilt motor. It's a 1992 Merc 7.4l Carbed with Thunderbolt 4 and RAW Water cooling. It was running just fine for the 20HRs during the breakin. I used SAE 10w/40 QakerState oil.
Well...
At 20hrs I did the first oil change. Here is where I may have gone wrong. I used Mobil 1 5w/30 synthetic and a Purolator PURE ONE filter.
I started it up and got my oil pressure.
It was my plan to run it one more time before winterizing the whole thing.
Everything looked good. Headed for the lake. Got out there and was cruising along anywhere from 3000-4000 RPM. Then I took it to WOT at 4400 RPM. Just fine. No problems. Stopped and sat there on the lake relaxing. Started it up again WOT for about 3 mintutes, no problems. stopped and just sat there again relaxing. Feeling good bout the LAST run of the year and enjoying the fruits of the freshly rebuilt motor. Thought to myself. Well, lets head back to the marina and go home and get her ready for the long winter storage.
WOT for about 5 mins and Oil pressure was steady as always, all of a sudden I hear a clacking come on from from the motor but I dont really feel a loss in power. Of course I drop the rpms down to a crawl and the noise dies off. There are NO other boats in sight and I am very close to the marina. I decide to creep in there. The ticking was still able to be heard faintly. When I got to the dock we turned off the motor. Then started it again with the engine hatch open. A definite clicking could be heard. When I put it into gear and the RPMs dropped you could barely hear it at all. Then put it back to neutral and it came back. I bumped the throttle and the noise increased volume. It appeared to be coming from under the valve cover. At that point we put it on the trailer and headed home.
(I will try to leave out the part where in my upset state of mind, I thought I could leap and clear the big distance from the boat to the dock so I could walk around to the front of the trailer to winch it up onto the traierl. Well, you can guess what happend to me)
Ok, after I got home (and put on some dry clothes) I started the motor and used a homemade stethescope to listen for a more precise location of the noise. It really seems that it is in the valve cover area.
I then did a compression test of all 8. I got 120 on all of them. I assume this could be a good sign that my problem possibly in the top end.
I proceeded to pull the valve cover off, which meant pulling the manifold elbow and loosening the mainfold to get to the 2 tightspot bolts on the outside of hte cover. I was hoping maybe a rocker arm bolt had come loose. But no. they were all still torqued at 40LBs per the manual. This is where my engine expertice comes to a close.
My questions.
Is there any time where a noise like this is just something loose that can be fixed or no matter what, am I looking at tearing this down?
Could this be a rocker arm making noise even though they are all still torqued at 40LBs?
What do you think/suggest.
Please no bashing me for anything I have done wrong with this situation. I need/suggestions help not criticism. I have seen people post their problems before and got replies like "What the hell were you thinking............and so on" I am lost as to what do do next.
Thanks guys.
I just finished the 20HR breakin on my rebuilt motor. It's a 1992 Merc 7.4l Carbed with Thunderbolt 4 and RAW Water cooling. It was running just fine for the 20HRs during the breakin. I used SAE 10w/40 QakerState oil.
Well...
At 20hrs I did the first oil change. Here is where I may have gone wrong. I used Mobil 1 5w/30 synthetic and a Purolator PURE ONE filter.
I started it up and got my oil pressure.
It was my plan to run it one more time before winterizing the whole thing.
Everything looked good. Headed for the lake. Got out there and was cruising along anywhere from 3000-4000 RPM. Then I took it to WOT at 4400 RPM. Just fine. No problems. Stopped and sat there on the lake relaxing. Started it up again WOT for about 3 mintutes, no problems. stopped and just sat there again relaxing. Feeling good bout the LAST run of the year and enjoying the fruits of the freshly rebuilt motor. Thought to myself. Well, lets head back to the marina and go home and get her ready for the long winter storage.
WOT for about 5 mins and Oil pressure was steady as always, all of a sudden I hear a clacking come on from from the motor but I dont really feel a loss in power. Of course I drop the rpms down to a crawl and the noise dies off. There are NO other boats in sight and I am very close to the marina. I decide to creep in there. The ticking was still able to be heard faintly. When I got to the dock we turned off the motor. Then started it again with the engine hatch open. A definite clicking could be heard. When I put it into gear and the RPMs dropped you could barely hear it at all. Then put it back to neutral and it came back. I bumped the throttle and the noise increased volume. It appeared to be coming from under the valve cover. At that point we put it on the trailer and headed home.
(I will try to leave out the part where in my upset state of mind, I thought I could leap and clear the big distance from the boat to the dock so I could walk around to the front of the trailer to winch it up onto the traierl. Well, you can guess what happend to me)
Ok, after I got home (and put on some dry clothes) I started the motor and used a homemade stethescope to listen for a more precise location of the noise. It really seems that it is in the valve cover area.
I then did a compression test of all 8. I got 120 on all of them. I assume this could be a good sign that my problem possibly in the top end.
I proceeded to pull the valve cover off, which meant pulling the manifold elbow and loosening the mainfold to get to the 2 tightspot bolts on the outside of hte cover. I was hoping maybe a rocker arm bolt had come loose. But no. they were all still torqued at 40LBs per the manual. This is where my engine expertice comes to a close.
My questions.
Is there any time where a noise like this is just something loose that can be fixed or no matter what, am I looking at tearing this down?
Could this be a rocker arm making noise even though they are all still torqued at 40LBs?
What do you think/suggest.
Please no bashing me for anything I have done wrong with this situation. I need/suggestions help not criticism. I have seen people post their problems before and got replies like "What the hell were you thinking............and so on" I am lost as to what do do next.
Thanks guys.
10-24-2002, 01:49 PM
#2
Registered
5w30 is a light oil to run in a boat, 20-50 is more like it. You seem to be describing lifter noise. Are you sure you filled it? Low on oil will cause the lifters to get noisy. Change the oil (filter leave on)and make sure it is full, start it and check it again. The oil lines, coolers, etc, can hold a lot of oil. I am sure it is just low on oil. I doubt for a short time of clacking you hurt anything if low on oil.
10-24-2002, 01:49 PM
#3
Were doomed!
Charter Member
did you rotate the engine over and check rockers or just a quick visual? The cam may be in the upright position right now and putting pressure on the rocker...thus you not knowing its loose! Try and move it to see if they are all still tight.....after that its anybodys guess! 
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-Wally
Money can't buy happiness, but it can buy horsepower. And I've never seen a sad person hauling a$$!
-Wally
Money can't buy happiness, but it can buy horsepower. And I've never seen a sad person hauling a$$!
10-24-2002, 01:54 PM
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Check to make sure the rockers are not contacting the rocker cover or the spring retainers. I believe some rockers had to be clearanced to keep from hitting the edge of the rocker cover on the intake side.
10-24-2002, 02:32 PM
#6
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How much oil pressure do you have at idle? Cut the oil filter open with a chisel or old style can opener and check for debris.
If it's in the top of the motor you may have a cam lobe going away or a push rod wearing out prematurely. Good Luck!
If it's in the top of the motor you may have a cam lobe going away or a push rod wearing out prematurely. Good Luck!
10-24-2002, 02:49 PM
#7
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Yea, that's what I'm thinking. A flattened cam lobe. The problem is that with the thin synthetic oil, the lifter may not have rotated correctly and took out the cam. This is something that's a real problem with synthetics and roller lifters.
My builder wants straight 40w oil and a max of a 50/50 blend of synthetic and barney oil.
My builder wants straight 40w oil and a max of a 50/50 blend of synthetic and barney oil.
10-24-2002, 03:08 PM
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If he is using a roller lifter and cam, I would not think that it would be wiped out. He also said that it was broken-in for 20 hours on QS 10/40. I agree that the cam could be an issue but I may disagree if it is a billet roller cam. I have seen several BBC in the past few months eat cams immediatly and they seem to be where the engines were dropped of at a rebuilder and instructions were to do a simple rebuild and cam change (std hyd). I wonder if the rebuilders are using generic cams and if that may be the issue.
Waveline24, what cam and lifter are you using?
Waveline24, what cam and lifter are you using?
10-24-2002, 04:02 PM
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I have a problem with both my engines that I am rectifying over the winter. Problem is... no windage trays, oil aireate (sp) at wot and pressure drops. This will do just what you say. I had to watch my oil level closely through the season to prevent aireation. I could only fill crankcase oil to add line on dipstick. Any more and pressure would start to drop at wot.
I personally don't think you hurt the engine due to oil choice. I would definately change it though and replace with 15-50 or so and cut open oil filter to look for wear surface material. I would also try run your oil level at the add line on the dipstick at first to verify aireation is not the problem. Hopefully your lifters will pump back up and your oil presure will return.
Now stop asking stupid questions
Seriously though... I've never seen people act poorly to others problems here on OSO. Now boatered is another story. Some real aholes over there.
Good luck,
BT
I personally don't think you hurt the engine due to oil choice. I would definately change it though and replace with 15-50 or so and cut open oil filter to look for wear surface material. I would also try run your oil level at the add line on the dipstick at first to verify aireation is not the problem. Hopefully your lifters will pump back up and your oil presure will return.
Now stop asking stupid questions
Seriously though... I've never seen people act poorly to others problems here on OSO. Now boatered is another story. Some real aholes over there.
Good luck,
BT
