mercury 2.5hp problems please help

[c5 swh]

hi there ive got a mercury 2.5hp 2stroke 2000 outboard.

It starts first pull no problems but theres no water coming out the tell tale just steam if anything.

Ive tried blowing up it doesn't seemed blocked. the impeller looks intact what else can it be?

would a small 2.5hp have a thermostat or water pump?

any info much appreciated

 

[Lakesailor]

The water passages are very likely blocked. You need to take the head off the leg poke out the various channels. Replace the impellor anyway. If steam is coming out of the tell tale at least some water is getting to the head, but not making it back to the exhaust in the leg.

 

[VicS]

Without a serial number I cannot be 100% sure of details but

No it does not have a thermostat.

Steam does indicate that the engine is overheating due to a lack of cooling water flow rather than just a blocked telltale

Yes it has a water pump ... you say you looked at the impeller ... thats it!

I would have replaced the impeller not looked at it and stuck the old one back!

Did you look at the condition of the housing?

It would be nice to try forcing water from a hose up the water tube from the pump to the powerhead but that might not be feasible without dropping the gear case off.
But there is, I beleive, provision to attach a hose directly to the power head for flushing. What happens if you do that?

The water tube could be blocked esp it its been run in muddy or sandy conditions.

The cooling passages in the cylinder block may be blocked. It is a relatively simple job to remove the cylinderhead and dig them out if necessary ... You'll need a new gasket.

EDIT I see LS suggests removing the powerhead from the driveshaft housing and poking out water channels under there. You will need a new gasket there if you do.

 

[Lakesailor]

The two arrows on the right in my piccy point to the holes which the water transfers from the block to the head, and back again. These are prone to blocking. In addition to cleaning them I enlarged them with a tapered reamer. A drill the next size up from the hole size would do, but only used slowly, in a handrill if you have one.

 

[MrCramp]

Been there and got the T shirt. Dissmantle as lakey says. did mine 4 years ago. It is the best engine I have ever had, light, powerful and reliable.

 

[Lakesailor]

Oh. One of the 6 bolts will probably snap, so you'll need to carefully drill out the remains and maybe re-tap the hole, or you may be lucky and the stub may come out with the drill.

 

[PetiteFleur]

Oh. One of the 6 bolts will probably snap, so you'll need to carefully drill out the remains and maybe re-tap the hole, or you may be lucky and the stub may come out with the drill.

Or if the thread strips completely you can get 'Helicoil' inserts which most small engineering works can do for you for a small sum. This what happened to me with a 2.2 Suzuki.