72 omc stern drive 225 overhting ???

[Rich Novak]

72 0mc stern drive 225 hp
I have the outdrive submereged in a drum
I changed the thermostst
I put a automotive water pump on
head gaskets are good
I have a very good stream out of the trunion
I takes several minutes after the thermostat opens for the temp guage to start moving towards the RED .
I shut it down b/4 it goes red
I noticed the water in the barrell is very warm is that normal ??
When the impeller is bad how ouickly does the motor overheat
Is it very difficult to change the impeller, I have the manual but it is confusing to me .
I have a lot more time than money.

Thanks, Rich

 

[Nivekt]

Re: 72 omc stern drive 225 overhting ???

If your not sure how long its been since the impeller was changed last than its a good bet its time. Also, one thing I always pass on, as I was recently dealing with an overheating situation, is that be certain it is actually overheating. Go buy/borrow an IR thermometer and aim it right at the sending unit at the top of the motor. Does this temperature reading match what your gauge is showing? If so, then its time to either pull that drive and replace the impeller or pull you exhaust manifolds and see how clogged up with rust they are.

I changed my impeller myself a month or so ago for the first time and although you have to be careful and take your time, it really isnt difficult.

You do have to make sure you have all the parts before you get started:

-Impeller kit to include new housing($40.00)
-Upper gear case seal kit(not absolutely necessary, but since you're going to have everything apart anyway
you might as well do it)($35.00)
-Possible need for a water pump shaft depending on how worn your current one is.($160)
-Permatex No. 3 gasket sealant.($8)
-Loctite 680 retaining compound. ($17)
-Retainer to housing shims. part no. 313202-313206 depending on what you have on there now. (These
are the color coded shims. You just replace with new whatever color ones are on there now($20.00
-Also, I used carb. cleaner to clean off all the old gasket sealer once I took everything apart. Just spray
some on a rag and wipe it all off. ($3.00)

Like I said, take your time, read through some manuals. Watch some youtube videos as to how the impeller housing comes apart and just dive in. The most expensive part, if it needs to be replaced, is the water pump drive shaft. Those can cost upwards of $160 so just hope yours is in good shape.

 

[Rich Novak]

Re: 72 omc stern drive 225 overhting ???

If your not sure how long its been since the impeller was changed last than its a good bet its time. Also, one thing I always pass on, as I was recently dealing with an overheating situation, is that be certain it is actually overheating. Go buy/borrow an IR thermometer and aim it right at the sending unit at the top of the motor. Does this temperature reading match what your gauge is showing? If so, then its time to either pull that drive and replace the impeller or pull you exhaust manifolds and see how clogged up with rust they are.

I changed my impeller myself a month or so ago for the first time and although you have to be careful and take your time, it really isnt difficult.

You do have to make sure you have all the parts before you get started:

-Impeller kit to include new housing($40.00)
-Upper gear case seal kit(not absolutely necessary, but since you're going to have everything apart anyway
you might as well do it)($35.00)
-Possible need for a water pump shaft depending on how worn your current one is.($160)
-Permatex No. 3 gasket sealant.($8)
-Loctite 680 retaining compound. ($17)
-Retainer to housing shims. part no. 313202-313206 depending on what you have on there now. (These
are the color coded shims. You just replace with new whatever color ones are on there now($20.00
-Also, I used carb. cleaner to clean off all the old gasket sealer once I took everything apart. Just spray
some on a rag and wipe it all off. ($3.00)

Like I said, take your time, read through some manuals. Watch some youtube videos as to how the impeller housing comes apart and just dive in. The most expensive part, if it needs to be replaced, is the water pump drive shaft. Those can cost upwards of $160 so just hope yours is in good shape.

Thank you for for your informitive reply will pull the exhaust manifolds and clean them first.
Checking the temp is a good idea ,I just replaced the sending unit for the temp guage,didnt seem to have a problem b/4 that , tonight I will put the old unit back in and seen what happens.
Thanks Again, Rich

 

[southkogs]

Re: 72 omc stern drive 225 overhting ???

It's tough (I think) to submerge the drive enough to get water running through the system. It's supposed to be this deep when operating:


If you've got this hose attachment on your unit, run some water in that to see if the system is cooling:


If you don't overheat running water in at the trunion, then you can localize back to your impeller. If you're still overheating, then you know your problem is up in the engine somewhere.

 

[Nivekt]

Re: 72 omc stern drive 225 overhting ???

Thank you for for your informitive reply will pull the exhaust manifolds and clean them first.
Checking the temp is a good idea ,I just replaced the sending unit for the temp guage,didnt seem to have a problem b/4 that , tonight I will put the old unit back in and seen what happens.
Thanks Again, Rich

Good luck Rich. Have a buddy around to help you pull the drive. It can be done alone(I did it) but it will take considerably longer. Make sure you build a drive stand. Pretty simple, just some 2 x 4's and a rolling cart if you want. Once you do this job by yourself you will have so much confidence in being able to work on any part of your setup. The only downside to tearing apart say, the lower, should you ever need to, is the need for all of OMC's crappy specialized/hard to find tools for taking apart absolutely everything should you ever need to.

 

[Nivekt]

Re: 72 omc stern drive 225 overhting ???

It's tough (I think) to submerge the drive enough to get water running through the system. It's supposed to be this deep when operating:
View attachment 173585

If you've got this hose attachment on your unit, run some water in that to see if the system is cooling:
View attachment 173584

If you don't overheat running water in at the trunion, then you can localize back to your impeller. If you're still overheating, then you know your problem is up in the engine somewhere.

Good point on the hose attachment southkogs. Rich, you really shouldnt need to submerge the entire drive to test properly and in fact, I would avoid it if you can get your hands on the hose attachment. Reason is that with the barrel method, you always run the risk of heating up the water in the barrel and getting unreliable readings the longer you run it.

Hose flushing kits/caps:

http://www.ebay.com/itm/OMC-Vintage..._Accessories_Gear&hash=item2a23c6638c&vxp=mtr

http://www.ebay.com/itm/OMC-Vintage..._Accessories_Gear&hash=item2a23c670e8&vxp=mtr

 

[southkogs]

Re: 72 omc stern drive 225 overhting ???

If you don't have the hose adapter and don't wanna' spend the $80 for one you can use a flush kit. Check out Howard Sterndrive's solution. Post #5 in THIS thread.