1997 350XL TBI raw water pump...risers...?

I have replaced the impellers on a regular basis. Risers and elbows are coming up on 4 seasons. Hours 780 +/- on the engines.

Recent slight steaming on one side, one riser and hose seems a little warmer, but no high temps. Fresh water cooled engines in salt water use.

Heat Xchangers and TBI injectors all new last season. This took care of several issues, including some high temps and fuel sheen in the exhaust outflow.

Engines 'allegedly' rebuilt 2014 +/-....mechanic suggesting new raw water pump assembly kits this winter, given age of pump assembly unknown. I am inclined to go ahead as it seems like good sense to know these get fully replaced given the unknown age of the current pump assembly.

I am asking the following given the above:

Any other major circulation/cooling functions to identify/replace while its torn open?

I am also considering another Riser job, (depending on Santa's generosity) would you go ahead with this with 4 years on em? Im leaning yes.

Should a head gasket job be considered given the steamer and some lower compression on that same engine?

( Im not good with tools BTW)

Thoughts and suggestions welcomed......TXS.

..............

Blackfin27 said:

I have replaced the impellers on a regular basis. Risers and elbows are coming up on 4 seasons. Hours 780 +/- on the engines.

Recent slight steaming on one side, one riser and hose seems a little warmer, but no high temps. Fresh water cooled engines in salt water use.

Heat Xchangers and TBI injectors all new last season. This took care of several issues, including some high temps and fuel sheen in the exhaust outflow.

Engines 'allegedly' rebuilt 2014 +/-....mechanic suggesting new raw water pump assembly kits this winter, given age of pump assembly unknown. I am inclined to go ahead as it seems like good sense to know these get fully replaced given the unknown age of the current pump assembly.
What type and name brand seawater pumps?
Belt driven... or crankshaft style?

I am asking the following given the above:

Any other major circulation/cooling functions to identify/replace while its torn open?
Above your manifolds you will have Elbows.
You may also have spacers/risers between the manifolds and elbows.
In each of these components, you will have seawater transfer ports.
Make sure that the transfer ports are clean and are not restricted by rust scale.

The seawater path (through the transfer ports) will vary depending on if you have what we call a Half Closed Cooling system or what we call Full Closed Cooling system.


I am also considering another Riser job, (depending on Santa's generosity) would you go ahead with this with 4 years on em? Im leaning yes.
Spacers/Risers typically outlast Elbows.
I would give more consideration to replacing the elbows.

Should a head gasket job be considered given the steamer and some lower compression on that same engine?
Before pulling cylinder heads, consider doing the following:
... pick up some hydrocarbon test strips, and see if hydrocarbons are entering your ethylene glycol coolant. If you see signs of hydrocarbons in the coolant, then that may indicate a head gasket issue.

... perform a cylinder pressure leak-down test to determine if the head gaskets are failing. The leak-down test will also reveal how well the valves and rings are holding or not holding.

... perform a cylinder pressure test to check the engine's over-all health.

Click to expand...

Blackfin27 said:

....
I am asking the following ....:

Any other major circulation/cooling functions to identify/replace while its torn open?

I am also considering another Riser job, (depending on Santa's generosity) would you go ahead with this with 4 years on em? Im leaning yes.

Should a head gasket job be considered given the steamer and some lower compression on that same engine?

( Im not good with tools BTW)

Thoughts and suggestions welcomed......TXS.

Click to expand...

It would be good to assess the state of the coolant and change it if required.

If you can afford it, changing the risers and elbows would be reasonable...if not, inspections would be warranted at this point.

a head gasket job isn't indicated by the 'steamer', the raw water side of the cooling system is and the two items above should address that.

the other thing worth looking into is the oil cooler - to make sure the zinc remnants haven't accumulated in the U-shaped passage where the zinc pencil goes.

Thanks for all the advice.

Coolant new with the heat Xchangers.

Oil cooler access is limited but will investigate.

Im going to do the sea water pump kit all new as the first step and see how my budget is. Then both risers and elbows.