OMC parts 800 / Cobra outdrive drawings * How to videos

T.C. Electronics/Marine (416) 751-7326 Home Page

OMC engine water pump not working? *See video

Pulling your hair out trying to troubleshoot your boats 400/800 series unit or engine cooling system?
Over heating?

  • Before you rush out and remove the outdrive so you can replace the water pump kit or impeller check the steps listed below

Exploded View Drawings
Search by part number or description here

Rad flush kit
Rad flush kit

OMC engine water flush kit

OMC engine water flush kit

OMC 400-800 water pump kit

OMC 400-800 kit

Engine flush kit

Engine flush kit

By author Trish Dougherty

Obtain a Seloc or stern drive service manual and read the section on OMC engine water pump and cooling system.

Place the boat in the lake not a pail of water or garden house with rabbit ears being placed on lower water pick area. This work great for outboards and Mercruiser lower units but not for 400-800 series lower unit do to the fact that unit is located in the upper gear case.

Install a radiator flush kit between the water pick tube up from the intermediate housing and the thermostat housing and check water flow. there should be a steady flow of water at 550 to 600 rpm. water should not have large amount of bubbles as water flow out of it.

If steady water flow is about 1-1/2 to 2 gallon per minute to fill pail then you need to check each manifold.

120 pounds of back pressure from the engine manifold leaking exhaust gas into the cooling area can stop or slow down the impeller from pumping. Low rpm will often cool engine and high rpm will not. Impeller can be damage from large exhaust gas leaks in minutes. This problem often come to life after the winter season layover.

Water flow area on the exhaust manifold should be clean every 400 hours or 5 years

Note to run the boat for short times say 5 to 10 minutes, you can run the garden hose into a radiator flush kit to cool engine and this will run water into impeller housing as well.

Engine location

Engine location

Engine flush kit
Engine location

OMC electric shift out-drives years 1966 to 1977 should not be left in gear for long periods of time, as electric coils have no way of cooling out of the water.

OMC did sell a flushing adapter kit OEM number 172914 for years 1979 to 1985. This was installed in place of old split bearing water cover reusing the same plate and gaskets.

Poor engine timing can also over heat engine but not a common problem.

Common problem with cooling is striped pump shaft, drive shaft or broken impeller housing but often impellers can last up to 10 or 15 years.

The above article are the opinions of our tech service rep Wayne Coll-Trish Dougherty is to aid in trouble shooting engine or kit installation but customer should obtain an service manual.