1991 Mercruiser 3.0L - Alpha I outdrive HOT

[larspeterson]

It seams my alpha one drive is overheating. The top of the drive is getting hot and the whole engine shaft is also getting hot and overheating my flex plate. The top of the drive will get hot to the touch when the boat is on step, but seams fine at low speeds when the drive is covered in water.

Any ideas on what I should look at first? The oil in the drive looks good and isn't low. The gimbal bearing and ujoint are new, so I don't think they are the cause of the heat.

 

[searay3]

Re: 1991 Mercruiser 3.0L - Alpha I outdrive HOT

Alignment is good? Drives do get hot. Not sure how hot as I have never put a temp gun on it. they sell drive showers to cool them but I don;t think a 3 ltr has the juice to over heat it....If the oil is good and the gimble/coupler is alighned, it is normal....

 

[dubs283]

Re: 1991 Mercruiser 3.0L - Alpha I outdrive HOT

its possible you have a restriction in the water passages in the upper half of the drive

 

[LilRedNeckGirl]

Re: 1991 Mercruiser 3.0L - Alpha I outdrive HOT

All drives get hot on plane when the unit is only covered on the lower section by water. A drive shower is a good idea if your running fast for long periods of time. being a 3.0 makes no difference, its still going to get hot. I would check also that you are getting the proper water flow out the manifold that dumps into the drive. If your water flow is low, the exhaust would heat the drive quickly.

 

[90stingray]

Re: 1991 Mercruiser 3.0L - Alpha I outdrive HOT

But if the flow is low i would think he would see an overheating condition at higher rpm's. How do you know it's overheating your flexplate?

 

[dubs283]

Re: 1991 Mercruiser 3.0L - Alpha I outdrive HOT

But if the flow is low i would think he would see an overheating condition at higher rpm's

not neccissarily, there are passages that surround the upper portion of the drive that don't have "flow" through them, they are just water jackets and if there is blockage at the base it could prevent water getting to the top but not block water flow to the bellhousing

 

[elkhunter338]

Re: 1991 Mercruiser 3.0L - Alpha I outdrive HOT

my 3.0 gets hot to the touch on plane, almost hot enough that you can't hold your hand on it.
No failure due to overheating in 100+ hrs of use, most is trolling but many 5-10 mile trips at a time.

 

[larspeterson]

Re: 1991 Mercruiser 3.0L - Alpha I outdrive HOT

Thanks for all the info.

The alignment is good, the flex plate is new and also the drive yoke. When I bought the boat there had been water intrusion in the bellows and this had damaged the gimbal bearing.

It seems to get hottest in the portion of the drive where it bolts to the bell housing. Is there a bearing there which may have been damaged from the water in the bellows? and if so where dose it get its lube?

With the boat out of the water I ran it in gear at 3500 rpms for 10 to 15 minutes (with the muffs on). Then I removed the drive and the u-joint and the drive shaft where extremely hot and I couldn't hold them in my hands but for a second. All the grease on the u-joint had melted. With the drive shaft at these temps I don't know how long the bearings will last......