Anyone ever replace rod bearings in a 2.7 without removing the engine ? Any pitfalls in doing so ? I'm thinking about this as a possible preventative maintenance item.
For those that have replaced rod and/or crank bearings, what's the latest word on the best choice of bearings (manufacturer/type) ? I've read that the factory tri-metal bearings may not have been the best choice. Not usre it that's absolutely true, but that's what I've read.
Not recommended-- especially as a pm item. You are asking for trouble. Chances are, if you need bearings, or have high miles, the crankshaft has to be polished or machined to make it last, or get it back to spec, not to mention correcting the original problem that caused any bearing failure, oil pump, sludge, etc. You can just install new bearings, engine in car, and run some emery cloth or sandpaper over the journals to clean them up, but mostly your wasting your time and just prolonging the inevitable, but not by much.
Best bet is to pull the engine, tear down, and inspect everything and assess total damage completely, and repair as needed. Other than that, time and $$$ wasted, bigtime.
In my opinion, if you are looking to change bearings as a maintenance item, my advice would be to leave well enough alone-- especially a major repair such as bearings. When it breaks, then worry about it. With 250(kms) chances are much of the other engine parts are significantly worn, and may need complete overhaul.
At present (260,000 km/161,000 miles), there are actually no apparent problems at all. The thing still runs like brand new and only uses about 1/3 quart of oil per 3000 miles.
Hence the idea to replace these hard working bearings before a problem develops.
One thing I had planned on doing when I do the timing chains and water pump, was also dropping the pan for inspection/cleaning. Of course my next thought was if I'd gone that far that I could also inspect the rod bearings by pulling the caps. And again if I'd gone that far and hadn't found any damaged bearings (and therefore no damaged crank journals), well I might as well replace the rod bearings. No ?
It can be done but but it really makes it difficult to measure bearing clearances and get them torqued down right.. By the time you are finished you will be thinking that it would have been easier to have pulled the engine..
You also run the risk of not getting one of them seated perfectly and you will be putting new bearings on an old crank with an old oil pump to lube everything.. just asking for problems...
In theory these bearings should last forever, since they are really just a spacer to float the moving parts in oil.. The bearing clearance and correct oil pressure and clean oil are the important things as it allows this oil film to always be between the moving parts...This is why regular oil changes and the correct weight of oil are important.. Just taking it apart and retorquing can change this critical bearing clearance...There is really no reason to suspect that the bearings are worn just based on the mileage on the engine...If they are making no noise ,oil pressure is good and you have no other signs of a worn bearing you would be better off leaving them alone..
you also can get a pretty good look at the inside of the oil pan when the front cover is removed for timing replacement so it may not be necessary to remove the pan..Just flush it out from the front without removing it..
Just my 2.7cents worth..
Well, now there's two knowledgeable guys discouraging the idea. And with good reasons in both cases. I'm sold !! I won't do it.
To be honest I was imagining doing the Plastigage thing 6 or more times over, while lying underneath the whole affair, and I wasn't liking the thought of it. I know it isn't a very practical way of doing this critical operation.
Thanks gents. I'll leave well enough alone. And I'll check oil pressure again before I buy the timing/waterpump parts to see of the oil pump has deteriorated since I checked the pressure last December.