rough engine that won't come up to full rpm's

[crieders]

Today after a lovely sail started my low hour Universal on c34, 1990 boat, 25xp and it ran rough and would not come up above 2000 rpm's. Oil check was fine. Any ideas as to what to check for? First our week trip cancelled due to Admiral's rib fracture and now the long weekend trip cancelled due to engine malfunction but hey life is great and wife at least now has a diagnosis for a pain that was worrying her.

[Stu Jackson]

Cliff, hope your wife continues to mend, sorry to hear about that.

Your symptoms all point to a fuel issue.  "Culprits" include the usual suspects of filters, intake screens in the fuel tank, the filter in the fuel pump and the routing of the hoses: tank to Racor to pump.

As a "regular" here you're most likely familiar with them all, not too many other things to check.

Let us know how you make out.

[crieders]

Thanks. My filters are all new this spring but who knows perhaps something in the fuel tank. I will have to check to see if I am getting clean fuel to the engine. Will meet a friend there 7 am to see what we can find. Kim is feeling better just knowing what is wrong.

[Ron Hill]

Cliff : With the little bit of info you posted - I'll guess that you got a bad injector/s. 

Glad the oil level is OK, because if the oil level is low enough to be a problem you can't believe the grinding and nashing sounds that would be coming out of the engine.  Not just rough running !!! 

A few thoughts

[crieders]

Found the culprit !!! After checking out the engine and finding no issues, one of the launch operators at Steppingstone went into the water and found a huge build-up of barnacles in a quantity so large that the shaft and prop could not turn !! I put the boat in the water around May 1 or so and have not had it bottom cleaned yet. Used Micron extra or whatever its called but I never paint my flex-o-fold prop.  The shaft, I do not recall as to whether it was painted. Never ran into such a problem so early in the season.
Anyway went out for a nice sail with family. Coming home into a 15-17kt headwind, I thought I'd run the engine for a while. We were moving along slowly against the tide, into the wind, obviously dirty bottom altho now with a clean prop and shaft. Slowly the temp rose to 200 degrees from usual running temp of 185. So I cut the engine and sailed to the mooring. I started the engine near the mooring and it immediately went back to 185 as we motored onto the mooring. When we checked the engine out before cleaning the shaft and prop, I did need quite a bit of antifreeze (no leaks noted anywhere) and I did not have quite enough. Probably could use a bit more which I will check on today.
Any thoughts specially about why the temp would spike like that?

[Stu Jackson]

Any thoughts specially about why the temp would spike like that?

Cliff,  Little antifreeze is like having an air bubble in your freshwater cooling system.  Kinda like NOT "burping" your engine after servicing your hot water heater or when replacing antifreeze.  Don't forget the 50/50 mixture of antifreeze and distilled water (unless you bought pre-mixed antifreeze).

[Ron Hill]

Cliff : If you had that many barnacles on the prop shaft you need to check the thru hull to the raw water intake!! 
Those nasties could easily have narrowed that opening and you aren't getting enough water!!  I'd also look at the impeller and make sure that all of the blades are in-place.  A few thoughts

[crieders]

Stu are you saying that the low antifreeze was because of an air bubble somewhere they suddenly was filled? Thats possible because I never got more than lukewarm water out of the hot water heater and its only 2 seasons old. As to the barnacles in the raw water intake, I was going to push a screw driver down from the inside and see what's there. Thanks.

[Hawk]

Cliff,
You didn't say whether you noticed a reduction in the water exhaust discharge as the engine overheated. Like Ron says a couple well placed barnacles in the thru hull will trap sea weed or anything blocking the water ingress. Disconnect the hose from the raw water filter and blow it out with your dingy pump. As you mentioned might need to poke out the stuck on critters also. Then open your thru hull with the hose still disconnected......thats the only time I'm really happy seeing water pour into the boat (:
A nice steady flow at least eliminates that as your problem.

Hawk

[Stu Jackson]

Stu are you saying that the low antifreeze was because of an air bubble somewhere they suddenly was filled? Thats possible because I never got more than lukewarm water out of the hot water heater and its only 2 seasons old. As to the barnacles in the raw water intake, I was going to push a screw driver down from the inside and see what's there. Thanks.

Yup.

I check my freshwater coolant every few weeks, and there's always room to add a little more.  2 years is a looong time...  One of the Critical Upgrades is to check your engine regularly.  Outta sight, outta mind...

Intake:  Hawk's Idea is OK, but it's a lot easier to take the inlet hose to the raw water pump off the pump and use a dinghy foot pump to blow the seacock clear.  My rw strainer is a bear to remove, it's just above the seacock, so to find if water is flowing, it's easier to simply take the strainer part off and see if there's flow, or take the hose off at the pump.

[Ron Hill]

Cliff : What you need is a coolant recovery system.  Then you don't have to remove the "radiator" cap to check the fluid level - just like your auto engine at a glance.  It's an expansion tank that takes the coolant overflow when the engine is HOT and then allows the overflowed coolant to get sucked back into the engines coolant reservoir when the engine cools. 
It also keeps the mess of the overflowing coolant from the port side of the engine and floor of the engine compartment.  It also allows seeing the coolant level in the bottle at a glance and know that all is OK.

I'm the one that started the "burping" of the engine after I replaced the seal on the engines internal coolant pump (behind the top pulley) and change my coolant.  Air will enter the water heater line and form an air block so the coolant will not flow and the engine will start to overheat.  That's what the butterfly valve on the top of the thermostate housing is for (stated in your engine owners manual).  I've outlined an easier way to burp - by manually pumping coolant thru the heater line to clear the air block.
I've never known anyone to get an air block from just checking the coolant level by removing the cap.  Doing anything that requires draining the coolant and then refilling - requires that you burp the line.

If you want to clear the engine thru hull of barnicles a foot pump won't do that.  Those critters have a waterproof superglue so they really stick.  I'd remove the strainer and use a 3/8" wooden dowel from the inside or go overboard and use the wooden dowel from the outside. 
The dink footpump will take care of jelly fish and soft sea grass cloggs, but hard cloggs require that wooden dowel!!

A few thoughts

[Stu Jackson]

http://www.c34.org/mainsheet/pdf/1999_no2.pdf

Picture of coolant recovery bottle, last article

[Hawk]

Stu
Good point as both times I had an over heat issue I first unscrewed the cap off of the raw water stainer....no water flow = likely blocked sea cock. Then proceeded to disconnect hose. Should have mentioned that.

Hawk

[crieders]

Thanks very much.

[Ron Hill]

Guys : I first wrote up a coolant recovery system with a RubberMaid quart bottle (with a picture like Stu has) in the early 1990s.