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290 SP-A Outdrive Servicing Dilemma!

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moresparks

Regular Contributor
I am currently undertaking the Biennial Bellows change on my outdrive and removed the drive to give a good overhaul and paint. I noticed that when I drained the oil it was very slightly coffee coloured. I put it down to the drain and fill plug seals!
I decided to do a pressure and vacuum test. I pressured up to around15lbs and this held for about an hour after this it lost around 0.5lbs an hour. The handbook says no more than the equivalent of 1lbs in 3 minutes. The Vacuum test was excavated to around 12in HG this held for around 15 minutes before slowly losing vacuum. This is still within the manual specification but not perfect. I have tested the tester and that’s o/k. But the loss is so small, the soapy water (pressure) and oil (vacuum) tests do not give a clue.
So… Should I worry? … I would appreciate any comments.
 
I'll post more this evening when at my PC.

Meanwhile, the 290 and SP -A are not quite the same.
Also, your press/vac tests should be holding.
I rarely see good seals continue to drop in press/vac value.
 
moresparks said:
I am currently undertaking the Biennial Bellows change on my outdrive and removed the drive to give a good overhaul and paint. I noticed that when I drained the oil it was very slightly coffee coloured. I put it down to the drain and fill plug seals!
I decided to do a pressure and vacuum test. I pressured up to around15lbs and this held for about an hour after this it lost around 0.5lbs an hour. The handbook says no more than the equivalent of 1lbs in 3 minutes. The Vacuum test was excavated to around 12in HG this held for around 15 minutes before slowly losing vacuum. This is still within the manual specification but not perfect. I have tested the tester and that’s o/k. But the loss is so small, the soapy water (pressure) and oil (vacuum) tests do not give a clue.
So… Should I worry? … I would appreciate any comments.
Click to expand...

I'll share a few thoughts here.


Your leak-down tests are not holding as I would have hoped for. Either the tester is leaking, or you have a breach somewhere.
Used seals may leak-down, but they should reach a point where they will hold.
If you've not replaced them or have any history of them being replaced, you'd best do so.

Eccentric piston seals fail and are often the source for water intrusion prior to the other seals.
Not always.... but most often.

Oil must be drained for the Pressure test.
For the vacuum it does not matter.

After a complete re-seal, I can get an upper, lower or entire drive to hold indefinitely.

I never remove an entire drive for bellows or universal shaft work.
I always remove the transmission first, install last.
With the transmission out of our way, it opens up the area for the shift cable clamp, S hose connection and water neck fitting work.
Much easier IMO.
 
Many thanks Ricardo – It’s good to obtain an expert view as you have just confirmed my thoughts. I don’t think the seals have ever been replaced to the best of my knowledge and the drives are over 20 years old now. I have most of the seals already except those by the Universal Joint.
It must be easier just to remove the Transmission as the drives are quite heavy especially trying to get them in and out of the boot of the car. But the boat is stored in a yard quite away from me and I can work on the drive during the winter when time and weather allows.
Once again – many thanks; you just don’t know how helpful your responses are to us enthusiastic amateurs.
 
You'll want to determine if this is a 290, 290-A or an SP-A.
The 290 uses the all steel bearing box, whereas the "A" uses the integral aluminum clamping collar/bearing box.
Seal and bearings are the same..... but the procedure is sightly different.


There's nothing wrong at all by removing the entire drive. My comment pertained to the ease of transmission removal first and installation last. You'll see what I mean when you go to re-install.
Your leak-down test can be performed while the drive is off.
I'd recommend that you pull the transmission again afterwards, as to keep the two O-rings fresh for final installation.


While you're installing the main drive seal, you will have the oportunity to press the main drive gear from the FWD bearing. This allows us to examine the races. The races will give us tell-tale signs of bearing condition.
No change to shim value will be created as long as you find and keep track of the shims that are just inside of the seal surface washer.
(this is for the Pre-A transmission)

NOTE: if the seal surface washer is replaced (again, this is for the Pre-A transmission), the shim value changes since not all of these are machined the same.
In which case the bearing box rolling torque value must be checked again, and adjusted.


If you go this far into the transmission, and if you were to find excessive wear, you may as well replace these 30207 and 31307 bearings.

The "A" and later Bearing Box rolling torque value is "crush sleeve" (aka "pre-tension sleeve") controlled.

Also, don't become confused with the data that you'll see regarding the manual's reference to "string line/spring scale" measurements -vs- "inch pound" center rotational force measurements.

The two values DO NOT cross over.

You'll also see a rolling torque value for both NEW, and for what Volvo Penta calls "run-in" bearings (used).


.
 
Hi.
What way round do you install the gear selector seal?
It seems I have one of the newer seals but no instructions. There are subtle differences. One side is flatter but with numbers stamped on, whilst the other has 8 slight indentations equally spaced around the edge. Also, the old seal was a devil of a job to get out as it was sealed in with sealant. Should I also seal the new one with perfect seal or similar? Or just use waterproof grease?
Thank you.
 
These seals are directional, so make sure that you install it correctly.

And watch out for the detent spring pin. We'll see two style eccentric pistons regarding the position of this spring pin.
If your eccentric piston is like the one shown in image #10 (pin being parallel with the piston... not perpendicular), this spring pin must be retrieved.
If not retrieved, in the future it will prevent the removal of the new spring pin that you'll be installing.

Simple solution is to spray carb cleaner into the bore.
The carb cleaner will reduce the oil film that may prevent the pin from falling out.
A light tap on a soft surface should cause the pin to fall out.



 
“Once again – many thanks; you just don’t know how helpful your responses are to us enthusiastic amateurs.”

I wholeheartedly agree big thanks to Ricardo



Dont know if this helps from manual (I have only seen the old type seal. I believe there is a black, brown and the newest type seal is blue?)

Lubricate the sealing ring abundantly and install it with the steel edge (small clearance) facing inwards the gear housing
 
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Yes, first generation was single lip black, next was single lip brown.... and after that was double lip green.

I highly recommend that you polish the eccentric piston surface where the seal rides.
Also, check the SS shim washers underneath the shift shoe adjustment bolt head. Rare.... but occasionally these will corrode some.


BTW, an old 280/290/SP style single prop line cutter (the long spacer/cutter that has lost the tin portion), makes a perfect press-in-tool for this seal.
Just dresss it up (as to not have any real sharp edges), and it will work great.
 
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