Bottom End Wear - Engine Out Job

[jonclancy]

Hi All,

You know of my Oil P problems posted elsewhere. I didn't know if the stuck plunger was the culprit, or if it lay elsewhere and that was merely a symptom. I was planning on refitting a standard sump I have had sodablasted and I painted in order to see if it was the shallow design of the custom sump that was having an effect. Seems not, because although Oil P was around 20 at idle after my run out to warm up the oil today, when I pulled the magnetic sump plug, I had a little Xmas tree!! The oil pan I used for draining the suump has small metal fragments in the bottom and the oil a silvery sheen. The Xmas tree became a grey paste when wiped on some kitchen towel.

Regardless of how it's happened, and I have driven the car on track days before the sump was changed, I think I now need to pull the engine and renew the bottom end. While I am there, I'll get the crank checked, wedged and balanced. When the engine was rebuilt around 2000 miles ago, it was re-seleeved back to standard bore and new pistons fitted - hopefully the bores are still A-OK. May as well get the conrods and pistons balanced as well. Block needed painting anyway!

I've attached a couple of pics below and have posted a few more in my photobucket here:

http://s94.photobucket.com/user/jonclan ... t=3&page=1

It's a bit of a bugger; as not only is there the expense, but it's put me back by X weeks in my masterplan.

Any advice welcome, but I intend to pull the engine and take the bottom end to a local engineering firm for assessment and the work.

Cheers

Jon

[Westfield 129]

Something in there is grinding itself away. The last time I saw that sort of sneeze powder in the oil was when the top ring land broke off of piston #2. This was also accompanied by a whole lot of oil smoke, killing every mosquito in Ventura County.

You will have a lot of cleaning to do before you use that block again.

I would not wedge the crank unless you were doing a full race engine, and even then... While lightening the crank is a good idea, you can get improved throttle response with an alloy flywheel, and save quite a few quid just having the crank trued and balanced. Better to spend the money on a proper block prep, and a very straight crank.

Of course, if the crank is really torn up... Then you will need another one, or yours will have to be welded and reground.

Balance and resize the rods. I also recommend line boring the block, and truing the deck. Everything needs to be precise, and straight. I budget $1,200 for the block blueprinting, 1380 offset bore, crank and rod prep and head freshening. It's expensive, but then I have not had to rebuild an engine to repair the last rebuild.

I have had excellent service out of the stock crank with a lightweight flywheel (Fidanza Alloy is a pretty good one, with a $45 replaceable friction face.

The cranks I use have been cross drilled (if necessary), oil holes chamfered, trued and usually polished as they generally don't need reground journals. I have yet to reground a crank in 6 A series engine builds. But then, none of those had metal floating around inside.

[jonclancy]

Hmmm, ring land could be the culprit - pistons were new when the motor was rebuilt, though. The proof will be when I get the head off and the lump out. In many ways, I hope so - the sump project has come a long way, and it would be great to prove it and do a run. The ground clearance is a huge improvement.

[Splat]

Bad luck, Jon.

I was just thinking about your sump project a couple of days ago. I'll be having one if it comes good.

[jonclancy]

I've got one you can fit next week, if you like! As a trial, mind....

[Splat]

Well, I could fit it next week, but with all of the suspension off the car at the moment, I fear that it'll still scrape

[jonclancy]

The engine is out - big thanks to Chris and Ian for their (continual) help!

Apart from the obvious, the ring-gear is damaged in a few places - properly edge bent - but I have a spare flywheel. Or we'll just get a new ring-gear fitted. My new starter motor has signs of wear on the drive, but the old one is worn too. I'll post some pics up, but will probably have to budget in for a hi-torque starter, too.

We're going to take the head and sump off tomorrow AM and see what there is to see. Wondering if an exchange engine would be easier, but, if this can be dealt with within a similar budget, we can get much more than the existing 55bhp.

Updates as they come.

Oh yes, I also found out what grounded over a speed bump at Combe a week or two ago - my exhaust box. Nice *big* dent in the underside. Bah!

[jonclancy]

And now stripped down to a short engine... light work when there are two people wielding spanners!

The custom sump was tricky to remove, even when inverted - no wonder it took a load of time and pain to fit when the car was on a trestle.

The first thing that jumped out at us was the state of the ring gear when we looked in more detail. Ouch!

There was lots of carbon on the piston tops and in the chambers, but I know the motor has been running rich for a bit.

We popped a couple of the big end and main bearing caps and there didn't appear to be armageddon in there. Thrusts too.

There appeared to be some marking on the cam lobes.

There were metal particles around the flywheel end main bearing, but the bearing itself looked pretty good. Should there be "running marks", or should the bearing faces be polished?

Cylinders looked great - honing marks still visible. The head looked fine, apart from the carbon.

I've posted some pics up here:

http://s94.photobucket.com/user/jonclan ... t=2&page=1

I'll be taking the crank out over the weekend and getting it ready to go for checking, chemical flushing and then decide whether the engineers or I will do the reassembly. I can feel the time pressure, and think that it will be worth paying to have the professionals do the job this time.

Any comments, recommendations or observations are always welcome.

Cheers

Jon

[Westfield 129]

It is likely that the oil pump is the problem. Take a look at the cam lobes and the lifters as well. You may have to replace the cam and the lifters.

The crank has to be measured, trued (usually, they are slightly bent) and if the journals are in good shape, polish. Otherwise, grind to specifications, and polish.

Truing is very important. Then balance the reciprocating assembly, rods, pistons, crank, flywheel.

Make sure that the block is hot tanked. When you get it back, clean it again with detergent and water, using block cleaning brushes. Make sure that you flush out the main oil galleries well. You might have the gallery plugs removed and threaded so you can install pipe plugs and really flush the galleries properly.

Line bore the block, true the deck, resize the rods. This will ensure that the rear slinger/spiral will work properly and that the crank will be running true in perfectly aligned bearings. All clearances should be optimum.

You should assemble the engine yourself. Not hard to do, and not that many parts. Get a solid ring compressor so that you just slide the pistons into the bore. None of that tightening of the rings...

I suggest offset boring to 73.5mm and new AE pistons, along with a proper vintage race cam (works like a hot street cam on a 1380 cc engine.

[jonclancy]

Thanks Jan. I'll be keeping the expenditure on this engine under control seeing as the car will be for sale when the various jobs are finished (so I can start building one of my own).

But, and it goes without saying, that the job will be done properly. I haven't taken the oil pump off yet, but will do so over the next couple of days when the rest of it is stripped.

I'll report back with what I find. I also read that WD40 is brilliant for removing carbon, so I'll give that a try, too. (Spray liberally, leave overnight, simply rinse off the next day for a perfect finish... )