4.3 V6, Circulating Pump Hose Bursting-How to backflush cooling system?

[Harbor Hopper]

I have twin 4.3 Mercs, 1998, with raw-water cooling. Changed the water pump impellers this spring. Port engine impeller was in bad shape. Also changed thermostat, but found no impeller pieces. Engine temp fluctuates between 150-170 constantly up & down, and the large hose from the circulating pump to the thermostat housing bursts after 1-2 hrs. I've went through 3 expensive hoses in a month, so something must be clogged and causing excessive pressure and the temp fluctuation. What is the proper method of backflushing the cooling system? Thanks in advance for any help!

 

[cr2k]

Re: 4.3 V6, Circulating Pump Hose Bursting-How to backflush cooling system?

We have found in some of the thermo housings there is a port you cannot see but when it gets plugged it will burst hoses also your engine may never warm up as it will also over pressure the thermostat causing by pass.

 

[Harbor Hopper]

Re: 4.3 V6, Circulating Pump Hose Bursting-How to backflush cooling system?

We have found in some of the thermo housings there is a port you cannot see but when it gets plugged it will burst hoses also your engine may never warm up as it will also over pressure the thermostat causing by pass.

When I changed the thermostats, I also cleaned the ports out very well. I am very detailed with my maint and do impellers & thermostats every 2 yrs.
The engine warms up just fine, but then fluctuates between 150-170. The stbd engine is constant at 150.

 

[Harbor Hopper]

Re: 4.3 V6, Circulating Pump Hose Bursting-How to backflush cooling system?

Anyone? There's gotta be someone that knows the proper backflushing procedure.

 

[NHGuy]

Re: 4.3 V6, Circulating Pump Hose Bursting-How to backflush cooling system?

It's not a procedure, it's logic. If you want to back flush take off the hose BEHIND every piece of of cooling hardware and run a probe, water, or air through the hose and component.
It sounds as if you have a major blockage though, find the coolant flow diagram and work on the area behind the hose that bursts.

 

[Harbor Hopper]

Re: 4.3 V6, Circulating Pump Hose Bursting-How to backflush cooling system?

Just wanted to update this. Back in August I took the waterpump off and thermostat housing (again). I flushed through each engine intake port (behind the waterpump) and got a lot of nasty water and tiny bits of impeller. I then flushed out the thermostat housing good and found lodged way inside, a larger piece of impeller. Problem solved! No more bursting hoses in the 200+ miles I've put on it since!

 

[Bondo]

Re: 4.3 V6, Circulating Pump Hose Bursting-How to backflush cooling system?

Just wanted to update this. Back in August I took the waterpump off and thermostat housing (again). I flushed through each engine intake port (behind the waterpump) and got a lot of nasty water and tiny bits of impeller. I then flushed out the thermostat housing good and found lodged way inside, a larger piece of impeller. Problem solved! No more bursting hoses in the 200+ miles I've put on it since!

Ayuh,.... Thank you for the up-date,....

Glad ya found the junk, 'n success...

 

[NHGuy]

Re: 4.3 V6, Circulating Pump Hose Bursting-How to backflush cooling system?

Glad you got er, that could get ugly.