2.4 refurb question

[Amstaff]

So, I pull my leaky 2.4 out to replace with my fresh 3.0.

The 2.4 was built for an autocross car but I don't know much about it. I was told that it is a 2.4 that was stroked or P/C's changed and now if has a 2.7 displacement. When I pulled the chain covers off I found that the "solid tensioners" that I was told were in it are actually normal tensioners with two nuts on them to keep them fully extended. Also, the chain housings are loaded with red silicone and I am afraid that it was used as a sealant throughout the engine.

Now my question.

Does it make sense just to tear it down, split the case and reseal it without doing anything else to it if the bearings and all look good? It runs good, no smoke or funny noises with plenty of power. It just leaks like a sieve.

[Flat6pac]

The red sealants get into the crank and plug the oil gallies.
Most sealants scum over before assembly so when the halves go together one side does not seal causing major leaks.
If you use three bond, read the instructions and apply to both side flange.
Bruce

[Trackrash]

I've been told that the case could warp. Others with more experience may chime in.

[Amstaff]

I understand how to seal it properly and what silicone can do when it lets loose (tons of reading material available here)

I have heard so much about the cost of rebuilding these engines because they require so much machine work like time certs, line boring etc..

Question is, is this really necessary on a good running engine or should I be able to split it, regasket, reseal and all be good?

[Flat6pac]

The biggest thing is cleaning out the oil passages through the total engine. I think you can reassemble after cleaning.
Bruce

[Henry Schmidt]

Originally Posted by Amstaff

I understand how to seal it properly and what silicone can do when it lets loose (tons of reading material available here)

I have heard so much about the cost of rebuilding these engines because they require so much machine work like time certs, line boring etc..

Question is, is this really necessary on a good running engine or should I be able to split it, regasket, reseal and all be good?

The problem with mag case 911 engines is that the case goes through all kinds of contortions during a normal heat cycle.
With enough heat (general use) the main bearing journals get oval shaped (top to bottom). When the engine is disassembled and then re-torqued, quite often the main bearings clamp down on the crank causing an unacceptable drag. I have even seen this phenomenon lock the crack so it is impossible to turn.
One well documented partial rebuild on this forum that featured the replacement of case through bolt o-rings and a re-torque of the cases. When the engine was restarted the builder erroneously thought the slow cranking was a weak starter but in fact the main bearings were out of round causing drag on the crank.
Is it possible that your crank will spin freely after re-torque: sure it's possible but I wouldn't bet on it.

[Amstaff]

That's what I am afraid of.

I guess my best bet is to pull it apart to reseal but don't split the case. Can I replace the through bolt o-rings one at a time and be safe or should I also leave them as is?

[Henry Schmidt]

Originally Posted by Amstaff

That's what I am afraid of.

I guess my best bet is to pull it apart to reseal but don't split the case. Can I replace the through bolt o-rings one at a time and be safe or should I also leave them as is?

Anytime your re-torque the case through bolts on a mag case 911 engine you run the risk of deforming the main bearings. Even if you do one at a time.

[Amstaff]

Thanks Henry, now that I am informed of the risks I guess I will have to decide whether or not to do anything to it. There isn't much to seal if I don't split the case. Maybe just pull what I can and hope it reduces the leaks.

[DSPTurtle]

Is it leaking from the case? And there around two dozen other seals not counting crush washers that can be replaced without splitting the case. Lol

[Henry Schmidt]

Originally Posted by Amstaff

Thanks Henry, now that I am informed of the risks I guess I will have to decide whether or not to do anything to it. There isn't much to seal if I don't split the case. Maybe just pull what I can and hope it reduces the leaks.

If you commit to doing what's necessary as you go, you could try replacing crush washers and o-rings and see if the crank tightens up. If it does, then take it apart.
That said: tightening the case perimeter bolts and case through bolts will have little effect on sealing a leaking case, so after all is said and done, you may end up splitting the case anyway.
My suggestion, find the budget and do it right from the start.
Cheers

[Amstaff]

It is leaking from every orifice. I think it is because of poor choice of sealer.

I think I will just pull the chain housings off, install new gaskets and seal them properly, do the triangle of death and replace the return tube seals (they are already 2 piece). That way I can use the engine and save my pennies for a correct build. I just finished my 3.0 build so my penny jar is a little low right now.

Thanks to everyone that chimed in!