I bought this 01 A4 1.8 with Auto last week not knowing why it was not running. It turned over but wouldn't start. Upon further inspection, I found 3 camshaft caps that were pretty worn due to lack of oiling and so I pulled the oil pan (PITA) to check and see if I need just a new head, or a bottom end too.

So far all the rod bearings look great but there is one Main Cap bearing that is scorned pretty bad. The crank looks good and the cap is fine, just the bearing looks terrible. The rod bearings look like new. See pictures below

Can/should I just replace the main bearing and put a new head on it or should I replace the whole engine? I was planning on flushing the engine a few times to remove any debris from the oiling system before running it. The car only has 74k mile on it and I hate to spend all that money if I don't have to.

What do you guys think, are these engines tough and will it recover with new bearings, or should I start over?

Audi Owner for 1 week and counting.......Need motor

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holy jesus, what happened to that car??

 

It'd probably be easier (and maybe even less expensive) to just replace the engine, but you could probably rebuild it. If you do though, redo it all - all new bearings, seals, rings, oil pump, t-belt assembly, etc. If the engine is going to be out and apart, that's the time to take care of all of it. Get the block hot-tanked and the cylinders honed by a professional engine shop (you might have them do your bottom-end assembly for you if you haven't done this before - it won't cost a huge amount and it'll give you peace of mind knowing it's in there correctly). If you're going to mod big, now's the time for rods too (if you're doing a turbo upgrade that requires stronger rods - if not, stay stock on the rods and save the money). Bottom line is, if you rebuild, do it all and do it right, and you can have what equates to a zero-mile engine in your car. It'll probably cost more this way though, especially if you use aftermarket parts. You can replace the engine in its entirety for less money (I would think, anyway) and certainly less downtime, although with a used engine you're going to want to go over it carefully and replace anything questionable (without a doubt, do the t-belt service at that time, before the engine goes in).

 

CIA- The Previous owner drove to a gas station when the oil light came on. Messed up the head pretty good but only one lower bearing damaged.

Thanks for the advice UpststNYA4
I ordered a good used 2003 AWM head yesterday and plan to take the block out and rebuild to stock. The only mods I plan on doing are those which increase the MPG. The car should have enough power for me in stock form. Any recommendations on bearings? I guess I can go with STD since thier appears to be little or no wear on the crank? The car has 74k on the clock. Again, thanks for all the advice.

Dave

 

An idea to check into - when I was big into the 300ZX scene, one common block mod that was done on the VG30 motors we had, was to port the main water galleys in the block. When the engine was apart, you could look down the water channels and see casting flash back near the #5 and 6 cylinders, which hindered coolant flow. Consequently, and not surprisingly, when a Z driver lost his engine to detonation, most of the time it was detonating in those cylinders, or if it was a severe meltdown, those two showed the worst damage. The coolant had a harder time cooling those cylinders than it did the other four, due to the blockage. When someone built their engine for real (or even rebuilt it to stock trim), they'd hone those coolant channels out to ensure even (and appropriate) coolant flow to the rear cylinders.

I don't know if this is an issue on the Audi engines or not, but it's definitely worth taking a look at. If you see casting flash in there, or obstructions of any other sort, have it honed and reamed out to maximize the efficiency of the cooling system on your engine.

 

Thanks for the tip UpstateNYA4. I will surely check that out when I have the motor apart.

Question: Do you need to use "Audi" RTV gasket material or can you use "Mr Gasket" or other store brand material? And are there any brands of timming belts to steer clear of? I want to use a good one but I don't want to pay out the @#$& for a brand name only.

 

hah i love when people do that. my boss was driving our crappy box truck, 2.2l turbo desil to somewhere, he was about 3 miles from the store when the CEL and oil lights started going off, pulled over to the side of the highway see that the entire side of the truck was black with oil. instead of calling me and asking what to do, he DRIVES BACK with zero oil. 5 minuits later he says to me hey whats wrong with the truck. i said well it needs a new engine now. and he seemed surprised for some reason.
/end threadjacking

 

I don't know for sure, but I would think any RTV is going to be fine. The only thing I'd wonder about is where the RTV is being used as a gasket that comes into contact with coolant. Since we use G12, a special coolant, there may be a reason to use Audi-approved RTV. I may be completely talking out of my a** here, but I suppose there's a chance that G12 could react with regular RTV and cause an issue. Again though, I don't know.