Merc MPI V6, cracking timing covers **UPDATE**

[Willyclay]

Re: Merc MPI V6, cracking timing covers **UPDATE**

but GM are being cagey about it and only supplying parts for those engines to people with VIN numbers so they can verify the parts are going on the right engine!

Non carborundum illegitimas!

 

[achris]

Re: Merc MPI V6, cracking timing covers **UPDATE**

Non carborundum illegitimas!

Trying not to....

 

[stackz]

Re: Merc MPI V6, cracking timing covers **UPDATE**

"Non reusable assembly. Replace upon removal" cast into it... It a one-time part! If you take it off, throw it in the bin!

I wonder why? its not like its a torque to yield bolt or anything? I'd find it hard to believe that it would purposely deform or something...well aside from the obvious cracking lol.

I'd almost keep one that has already cracked and grind out the crack and refill it with epoxy and then brace it on the outside portion somehow just to experiment with. but then again, you have to remove the engine from the boat for the experiment which almost makes it not worth it. though, you seem to be an expert at it at this point.

hopefully the aluminum cover does the trick man!

 

[FreeBeeTony]

Re: Merc MPI V6, cracking timing covers **UPDATE**

Non carborundum illegitimas!

Illegitimi non carborundum is a mock-Latin aphorism meaning "Don't let the bastards grind you down".

Now I'm learning Latin from this site..........what's next??

 

[John_S]

Re: Merc MPI V6, cracking timing covers **UPDATE**

I wonder why? its not like its a torque to yield bolt or anything? I'd find it hard to believe that it would purposely deform or something...well aside from the obvious cracking lol.

My guess is that the gasket seal which is part of the plastic cover becomes deformed, and that is why it can not be reused. It looks like a raisd silicone bead.

I was able to change mine (for cam change) in the boat, but still wouldn't risk a used one. Just too much stuff to take back off, by time you can test it.

 

[NHGuy]

Re: Merc MPI V6, cracking timing covers **UPDATE**

I have a (perhaps stupid) idea. Now don't shoot me if this doesn't work for you, but I'm just throwing it out.
Before you bolt it up you could dry fit it with some carbon paper in the high spots, the black mark will show you where to grind. That's how my dentist fit checked my caps!
With the motor out of the boat do your grind, seal & install of the parts. Now block off the crankcase everywhere & put a few psi of air in there to check it. Or does it not crack til you run it?

 

[achris]

Re: Merc MPI V6, cracking timing covers **UPDATE**

I have a (perhaps stupid) idea. Now don't shoot me if this doesn't work for you, but I'm just throwing it out.
Before you bolt it up you could dry fit it with some carbon paper in the high spots, the black mark will show you where to grind. That's how my dentist fit checked my caps!
With the motor out of the boat do your grind, seal & install of the parts. Now block off the crankcase everywhere & put a few psi of air in there to check it. Or does it not crack til you run it?

Not a stupid idea... Buttttt, when the gasket is not in place the gap between the oil pan and timing cover is about 3 mm... The gasket is one of those rubber formed ones. Once it's put in the oil pan groove it then applies pressure to the cover, and if it's too much pressure the cover breaks. If the pressure is not quite enough, it leaks... This is a real Goldilocks job this one.... :facepalm:

If the pressure is too high, the cover will survive a few weeks, or months (depending on how much too high).... Nope, doesn't break immediately.... The best one I had lasted 5 months...

 

[NHGuy]

Re: Merc MPI V6, cracking timing covers **UPDATE**

Could you just lose the gasket & put RTV in where the pressure point is? Maybe run the motor on a pallet after you do it to try it out.

 

[Pete104]

Re: Merc MPI V6, cracking timing covers **UPDATE**

Much earlier you changed the cover with engine in boat. You said (I may be wrong) that you either pulled the dowel pins or pushed them in. Are they reinstalled since engine is out?

 

[achris]

Re: Merc MPI V6, cracking timing covers **UPDATE**

Much earlier you changed the cover with engine in boat. You said (I may be wrong) that you either pulled the dowel pins or pushed them in. Are they reinstalled since engine is out?

Never done the job without pulling the engine out. Not enough space under the engine to get the sump out, and the back 2 nuts for the sump would be impossible (I mean REALLY impossible, not just difficult) to remove with the engine still in place.

Originally dowel pins were in the original cover and located in the holes in the engine. All the new covers have the dowel pins locked in the engine block and the cover locates on them. Yes, I have checked all those. If they were out of position the main oil seal would also be leaking, but it isn't. I have checked the clearance between the oil seal and the crankshaft with the cover in place and it is PERFECTLY centred, nope, that is not the problem. Somebody said earlier, the plastic cover is pish, I agree. That's why I will wait until the ali timing cover and the oil pan to match it, arrive. I suspect that (God, I hope!!!) will solve this problem for good....

Chris.......

 

[Pete104]

Re: Merc MPI V6, cracking timing covers **UPDATE**

Just had to ask.

Good luck!

 

[Saline Marina]

I hope this is not out of line (mods, if so, please delete) but I was going to link a thread to a similar issue I had on a 2000 Four Winns 170 Horizon with 4.3GL Volvo and the way I repaired it. I hope it could help someone following this thread in the future. My opinion on the "replace entire asm upon removal" is that the RTV "squirts" that get applied at the corners in the engine plant are bonded strongly enough to crack pieces of the cover off, and if all the original RTV isn't cleaned off its a guaranteed leak path pretty much. This happened when I removed my plastic front cover, but small enough to work around. I would agree that GM probably had a serious warranty or field issue with this design, hence the aluminum cover in future model years. In my case I just did the repair in the boat, by using an extra dose of RTV all the way around anywhere oil could leak below the pre-formed upper gasket. I don't have much runtime on mine other than running on the water muffs but I will pursue the aluminum front cover if this doesn't work. I felt like in my case the arc of the lower oil pan gasket was recessed from the front face of the engine block slightly, sort of the opposite problem that Achris had where it was slightly proud. Its like they were expecting a cast surface to be as well controlled as a machined one, from a dimensional standpoint, and the flexibility of the gasket to makeup the difference in the variation. I think we can see from these fails and required repairs that there's definitely a common problem here that probably thousands of others have had.

http://forums.iboats.com/forum/engin...il-leak-repair

 

[achris]

Can't use an aluminium cover on the blocks with composite covers, the drilling is different, and I think the casting itself may be different to accommodate the larger (ali) cover.

Hope your fix does the trick. I did try tha at one stage, but the oil tracked up and out of the RTV 'patch', that's why I went the extra (of pulling the engine repeatedly) to get it all right. Been over 12 months since the last leak. I'm still holding my breath, and checking the front of the oil pan after every trip (probably will for the rest of the years that engine stays in this boat)....And given it's 8 years old now, that will probably be another 4 to 6 years.

Chris......

 

[rderenzy]

Just to be correct... I'm not able to upgrade my cover from plastic?

 

[achris]

Just to be correct... I'm not able to upgrade my cover from plastic?

That is correct. I'm still oil-free BTW.... (Brand new pan and cover. From GM, not Merc!)

 

[Alexanderjaldin]

Re: Merc MPI V6, cracking timing covers **UPDATE**



Never done the job without pulling the engine out. Not enough space under the engine to get the sump out, and the back 2 nuts for the sump would be impossible (I mean REALLY impossible, not just difficult) to remove with the engine still in place.

Originally dowel pins were in the original cover and located in the holes in the engine. All the new covers have the dowel pins locked in the engine block and the cover locates on them. Yes, I have checked all those. If they were out of position the main oil seal would also be leaking, but it isn't. I have checked the clearance between the oil seal and the crankshaft with the cover in place and it is PERFECTLY centred, nope, that is not the problem. Somebody said earlier, the plastic cover is pish, I agree. That's why I will wait until the ali timing cover and the oil pan to match it, arrive. I suspect that (God, I hope!!!) will solve this problem for good....

Chris.......

Hi Chris!
Thnx for sharing about your problem! I seem to be having the same issue going on with my 2007 4,3 MPI. Just a couple of questions to clarify:
Can I get a aluminium cover if I also change the pan?
Or do I get a new plastic cover and change the pan to prevent the new cover from breaking the same way?

Many thanks in advance

From Sweden,

Alex