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Revotec fan fitting


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I am looking for advise on how to remove the bolt holding the fan extension to the crankshaft. I cannot seem to prevent the engine turning over as I try to undo the bolt. What’s the magic answer?

Hopefully someone can guide me.

Mike

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Can you get a large stilson (self tightening) wrench onto the extension nose and spragg it against a suitable chassis or bodywork area to stop it turning and use an impact gun on the crank dog bolt on the nose (that works on my Stag). Or get the wife to stand on the brakes with the car in gear and chocs behind the wheel. 

I tighten these crank dog bolts (5/8th UNF from memory) on the Stag and 4 cylinder TR to 120 lb ft so they are tight (necessary).

Mick Richards

 

Edited by Motorsport Mickey
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I would do as Mick says.

Also spray a couple of times with WD40 or similar on the bolt head “bottom” and the connection between extension piece and crank shaft and leave for a day. The bolt head is “rounded” so make sure you have a proper fitting tool.

Mine came off relatively easy.

Waldi

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I found that the ‘never before removed’ crank pulley bolt on my previous TR6 came off quite easily with the mains powered Clarke impact wrench.

the Makita 18v impact wrench would not move it.

steve

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If you are fitting a Revotec electric fan why are you removing the big crank bolt?

The original yellow mechanical plastic fan is attached by 4  off  hexagon headed 5/16" unf screws to the crank extension, these are lock tabbed and require a 1/2" AF spanner/socket to undo....or is this a Triumph 2500S engine with blue, red or natural coloured plastic fan and viscous coupling?  

Cheers

Peter W

Edited by BlueTR3A-5EKT
fan colour
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Thanks guys. A few things to try. I will have to remove the grill to get my Clarke impact wrench in, but that might be the way forward if Micks Stilson idea doesn’t work. The fan is off, but the fan extension needs removal Peter, to give room for the Revotec fan to fit on a TR5. I will get there in the end.

Mike

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50 minutes ago, harrytr5 said:

Put rope down the bore and compress the piston onto to it. This will lock the engine and prevent it turning.Leave a length out of the plug hole so you can extract it.

Works for me!

Regards Harry TR5 Nutter

If you do this undo the rocker shaft from it's studs and allow all the valves to shut first, otherwise you risk bending a valve stem when the piston crams the rope upwards, at some stage it will become solid.

Mick Richards

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Mick makes a good point (as always).

Does anyone know how much torque could applied before bending a con rod or slightly twisting the crankshaft.

I know this is an issue on small engines with “assembled” (not forged - or cast - one piece) crank shafts.

I the piston is near TDC the force on the con rod  can be very high, much higher than the force applied on a wrench. 
Or is this a non-issue?

Thanks,

Waldi

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Anyone tried wrapping the extension in foam with plastic cover and injecting freezer spray.

Same technique as freezing plumbing pipes.

Wickes Kit I use on plumbing  https://www.wickes.co.uk/Wickes-Pipe-Freezing-Kit/p/424921

???That should cause the extension to contract, taking tensile load off the bolt and perhaps allow it to undo???

Could also try the modern mechanics undo trick on the head of cylinder head bolts. Give them a clonk sideways with a brass drift and club hammer. 

Cheers

Peter W

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9 hours ago, harrytr5 said:

Put rope down the bore and compress the piston onto to it. This will lock the engine and prevent it turning.Leave a length out of the plug hole so you can extract it.

Works for me!

Regards Harry TR5 Nutter

I've used that method with all the rocker gear and head stud nuts removed to break the bond of a cylinder head gasket so that I could remove the cylinder head which stubbornly refused to shift. A quick turn over on the starter motor and boom, job done. That was at a race meeting when the head gasket blew in morning qualifying and I managed to get it sorted to be able to take the start at the afternoon race.

On 12/29/2019 at 10:52 AM, Aldpilot said:

I am looking for advise on how to remove the bolt holding the fan extension to the crankshaft. I cannot seem to prevent the engine turning over as I try to undo the bolt. What’s the magic answer?

Hopefully someone can guide me.

Mike

I'm also wondering how to remove that front crank nut on my TR5 engine which is now out of the car on a stillage ready for a full rebuild as part of the car restoration, see below. I meant to use the "someone else on the brakes and chocks under the wheels" method as Mick mentions and I've used successfully before - but I forgot before I took it out of the car. I was considering removing the clutch and bolting a flat bar approx. 500 - 600mm long to two of the flywheel bolts with one end on the floor to resist the undoing torque.

I've recently treated myself to a 20V battery impact wrench, so I'll give that a try first, as recommended above.

Dave McD

IMG_0002.jpg

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All sorted today and my nice new Revotec fan is fitted and working. Tried the impact gun (with a long extension), but that didn’t shift it (that surprised me). Mick’s idea of the large Stilson on the stubb extension and a long breaker bar on the crankshaft bolt worked in the end. It was done as a 2 man job, with one holding the Stilson and the other on the breaker bar. The Stilson was a bit big to get set against anything substantial enough, so was hand held by my assistant. It all worked a treat. I would think that should work for you Dave McD if the buzz gun doesn’t do it.

Thanks to everyone for your ideas and help.

Mike

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Hi,

I alway did it on all my engine with a 7 m nylon rope d=5 mm through the spark plug bore.

The valve and rockers need no attention at all if you make shure you do it on the compression stroke of the cylinder *.

So this is little effort and works within a few minutes.

I know the worry about bended con rods and cranksafts -

but keep in mind the power of the runing engine on the con rods and crankshaft.

In my opinion this is a needless worry.

Ciao, Marco

* mind the side of the TCD you are to slack / lock the center bolt (to block the engine forwards/ backwards)

Edited by Z320
7m d= 5 mm
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