Can a radiator shop clean an exhaust manifold ?

[alan ber]

Engine started too get hot, time too change lower unit impeller

1984 Mercruiser
alpha 1
4 cylinder
488 engine
4 barrel carb
self contained cooling

Thinking too myself Didn't I do this recently ?
Could not remember but jumped back into the job again.
I live in Fl and boat used few times a month but short trips

After a few local fishing trips, temp gauge was getting hot ? System of impeller again ?
Pulling intake hose from lower unit that takes water too heat exchanger, No water was pumping. ( damn , again )

Have done impellers many times, thinking this is not right, maybe something else is not working causing impellers too burn out
I brought it too a local shop I use at times

During past months boat has been back too shop number of times.
I am now on impeller # 4
Picking up boat yesterday impeller was No Charge .
Shop owner tells me impeller fins were melted like I ran with no water, but I know better.

Shop owner states he would almost guarantee my impeller issues is related too exhaust manifold
After install of impeller we start boat
Ran on rabbit ears 20 minutes , temp gauge stays cool .

Mechanic aimed a heat infra ray gun at exhaust manifold
Heat was different in 4 different areas of exchanger getting hotter as it went from water intake too transom
Temp was 119 -125- 130- 134 going from intake towards transom
He stated temp should be almost the same all the way down the exchanger
There is no leaking of water and no indication of any other exchanger problems

A guy was adjusting rabbit ears and stated rabbit ears should have a slight pressure feel holding ears too lower
But he indicated none

Mechanic stated he would almost guarantee my exhaust manifold needs replacing which is why I keep burning out impellers?

Sounds like it makes sense , DOES IT ?


If that's the case can a radiator shop clean manifold ?

Used is risky, new costly, considering I am thinking about selling getting a larger boat ?

THANKS

 

[Fishermark]

Re: Can a radiator shop clean an exhaust manifold ?

To your basic question - no. If the manifold is clogged, it is clogged with rust and corrosion that used to be metal. No way to safely clean it out. Best to bite the bullet and buy a new manifold.

Now, can a plugged manifold cause the impeller to burn up? I cannot see how that could happen - unless the water had absolutely nowhere to go. I would examine other causes. When you run it on muffs (is that what you are calling rabbit ears?) make sure you have plenty of water pressure. Water should be running out and around the muffs, and yes, they should fit fairly tight.

 

[midcarolina]

Re: Can a radiator shop clean an exhaust manifold ?

I would be checking to see if the HE is clogged/plugged with debris.......

 

[alldodge]

Re: Can a radiator shop clean an exhaust manifold ?

Engine started too get hot, time too change lower unit impeller

1984 Mercruiser
alpha 1
4 cylinder
488 engine
4 barrel carb
self contained cooling

Thinking too myself Didn't I do this recently ?
Could not remember but jumped back into the job again.
I live in Fl and boat used few times a month but short trips


After a few local fishing trips, temp gauge was getting hot ? System of impeller again ?
Pulling intake hose from lower unit that takes water too heat exchanger, No water was pumping. ( damn , again )

Have done impellers many times, thinking this is not right, maybe something else is not working causing impellers too burn out
I brought it too a local shop I use at times
During past months boat has been back too shop number of times.
I am now on impeller # 4
Picking up boat yesterday impeller was No Charge .
Shop owner tells me impeller fins were melted like I ran with no water, but I know better.

Shop owner states he would almost guarantee my impeller issues is related too exhaust manifold
After install of impeller we start boat
Ran on rabbit ears 20 minutes , temp gauge stays cool .

Mechanic aimed a heat infra ray gun at exhaust manifold
Heat was different in 4 different areas of exchanger getting hotter as it went from water intake too transom
Temp was 119 -125- 130- 134 going from intake towards transom
He stated temp should be almost the same all the way down the exchanger
There is no leaking of water and no indication of any other exchanger problems

A guy was adjusting rabbit ears and stated rabbit ears should have a slight pressure feel holding ears too lower
But he indicated none

Mechanic stated he would almost guarantee my exhaust manifold needs replacing which is why I keep burning out impellers?

Sounds like it makes sense , DOES IT ?


If that's the case can a radiator shop clean manifold ?

Used is risky, new costly, considering I am thinking about selling getting a larger boat ?

THANKS

I think you have an issue with getting the water into the impeller, and from there into the engine. See if you have a restriction in the lower section of the drive. What does the pump housing look like?

I take it you pull water through the drive and not from a thru hull fitting and strainer

 

[Scott Danforth]

Re: Can a radiator shop clean an exhaust manifold ?

my guess is there is debris from an earlier impeller lodged between the raw water pump and the engine.

was the system back flushed during the impeller change?

also, when running on muffs, always use the maximum amount of water you can get to the muffs, and never go above 1500 RPM. the waterpump in the leg will move 20 GPM of water. the average flow of a 3/4" garden hose at full pressure is 10 GPM, the average flow of a 1/2" garden hose at full pressure is about 5gpm