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melodyoferror · 17-10-2015, 01:01

Hi guys nothing is ever easy first i bought a boat from thatEpay place then find the 4-71 Detroit in the boat has a stuck cam shaft .
Now to get that stuck shaft out is a major job as the flywheel housing must be exposed to remove the engine management gearing. But i have to take the transmition off this may sound wierd but i am stumped as i dont know what the tranny is or how its fixed on to the flywheel .
can anyone fill me in ;;
l have all the bolts on the G/box undone
And she will rotate but it wont slide back away from the D/D 4/71
I have used jacks between the mounts to try and give a bit of room for a wedge no luck there even with a bit of sledge hammer.
And ref to the bolt heads i can feel on the face of the flywheel there is no accsses for a spanner i think it maybe stuck by corossion in the spiget
Has anyone got any expieriance seperating engine from gearbox .
The 4/71 has only 900hr on the meter and the bearings are like new .but the boat was swamped and needs a full rebuild if only i could get that dam transmition off needless to say both moter and gearbox are old but can be still good again with a little bit of your expieriance 17/10/15 cheers hope to hear from you soon

melodyoferror · 17-10-2015, 01:31

Ref to 4-71 what options do i have i am thinking its the spiget siezed in the flywheel or do they have a flexplate meshed onto flywheel that MUST be unbolted if so how did they get to those bolts ? anyone

**GordMay** · 17-10-2015, 05:24

Greetings and welcome aboard the CF, melodyferror.

melodyoferror · 17-10-2015, 05:28

Thanks for your reply and hope someone has some expieriance with my consern cheers

Doug Brown · 17-10-2015, 06:03

Not exactly a 4-71, but on Jaguar XJ-6 engines with automatic transmissions you remove the bolts holding the flex plate in place by putting your socket in thru the starter motor hole.

Obviously, the starter motor has to be removed to gain access.

Then you undo and remove a bolt, then rotate the engine to get to the next one, etc.

Once all the flex plate bolts are undone, you can then unfasten and remove the trans.

As mentioned, don't know if this will work for you but this might be how you have to remove them.....

**HappyMdRSailor** · 17-10-2015, 06:05

It's hard to understand your post, but it sounds like your tranny shaft is rusted stuck in the end of your crankshaft... Lots of wiggling, working back and forth and penetrating oil if you can access the shaft... sounds like a yes if you can feel flywheel bolts....

captain58sailin · 17-10-2015, 06:09

What kind of transmission do you have?

melodyoferror · 17-10-2015, 06:27

Thanks for ur knowladge but unfortunatly both are impossible to reach i have the starter out and i can feel a bolt head around the face side of the flywheel with the tip of my finger and there is no way you can get a spanner in that way. The only avenue i can get to those bolts is to cut a slot in the flywheel houseing .With that said how did the guys put it together so that makes me think the whole gearbox unit slides in through ??? (the flexplate )(then into the spiget i think thats where there is a corrosion problem
Again thanks for your in put but i am hoping that someone out there has dealt with the detroit setup before i use the wrong approach

captain58sailin · 17-10-2015, 06:45

What brand is your reduction gear? I have just removed a 471 and reduction gear from my vessel and I had to separate them in the engine compartment before hoisting them out, so I have experience with one particular type of reduction gear, which if it is not the same as yours will not provide you with any kind of enlightenment and possibly confuse the issue.

melodyoferror · 17-10-2015, 07:17

Quote:

Originally Posted by melodyoferror

Thanks for your reply and hope someone has some expieriance with my consern cheers

What type of reduction you ask well its spec tag is missing .. it has a lift lid oil fill cap on the top of box .on top to the right there is the forward reverse control forward of that is the dip stick straight down next to the mount on the right ...to the rear there is a hydrlolic pump and acc seems like what you would call a dual option or twin .below that ..the main drive is central with 6 ribs cast into the surounding plate but only at the lower part the plate of the main drive sound familuar .this may be an allison box but i cant verifie from the pictures ive seen on the net

captain58sailin · 17-10-2015, 07:57

Can you post a photo?

sy_gilana · 17-10-2015, 08:09

Could be a PRM box.

You need to make sure the propshaft is not pushing fwd. I made wooden blocks and removed the engine mounts, allowing the motor to slide forwards.

The tranny has a thick splined shaft that inserts into the drive plate. This sounds rusted to me.
You might have to break the plate, they are not expensive.

Do keep at it though, at 700 odd hours, the engine is not yet broken in.

Damn fine engines!