Engine time

[Stanley]

Coming back from Torrance, stopped at the grocery store. Didn't notice any problems. Came back and started it up, big cloud of whitish smoke from the tailpipe. Drove home, just a couple of blocks. Less smoke while driving but still a good bit. No loud clunking noises but heard some intermittent rattling like gravel in a can that seemed to come from the bottom of the engine. Pulled into the parking spot. When I turned it off, saw smoke coming from under the hood. Popped the hood and saw it was coming from the air cleaners. Oil was down a quart, but it was about right last week and it doesn't burn oil.

Don't really know, but my guess is it broke a ring and a piece went down in the oil pan. The smoke smelled like oil, not steaming coolant. Coolant temp was below normal.

I'd be bummed, but I'd been planning to rebuild it or get a new engine soon anyway. No point in paying to fix a broken ring or whatever it is now and then rebuild it later.

[Captain Obvious]

Holed pistons are one of the possible outcomes of running very lean.

You weren't getting like 35 mpg for the past couple weeks or anything, where you?

(Just kidding... Here's to hoping it's something simple and not serious!!!)

[Stanley]

It's possible. Didn't have it on the freeway though, and the temp never got over 175F. When I first changed the needles and installed new points a couple weeks ago had the mix very lean, took a drive and noticed extra heat in the exhaust manifold area. Had to stop several times to re-adjust mix and idle and it was almost too hot to adjust the mix. It was only like that for a half hour of driving but maybe it cooked something. More recently it was only slightly too lean. Took the mix down another 1/12 turn yesterday and the 5 mph burbling was barely noticeable and didn't affect driving.

Been planning to rebuild anyway though. Wanted to take it around to some shops and figure out who I wanted to the work, and get it done it in the fall while I'm on a long camping trip in a rented minivan. But once again reality has reared it's ugly head. It's my daily driver so I need to deal with it even though I'm swamped with work right now. Don't want to pay $1200 or so to fix a broken ring or whatever it is, and then do a complete rebuild or buy a new motor 4 months from now. 

[Zed Head]

There has to be a used L series engine out there somewhere that you could swap in.  They're surprisingly durable.  Even a junk yard engine would probably get you by.

Despite the weird noises there's always a chance that it's just a head gasket.  Might just pull the head first.  And/or drain the oil and see what's in it.

[Stanley]

I could use some advice on this. Need a first-rate shop in LA South bay, San Pedro or Long Beach to do the R&R. Also a engine builder, preferably in the South Bay or at least Southern California, but engines can be shipped so not necessarily. R&R and engine builder could be the same.

Also wondering what I should do with this. I've got a stock '73 240 with SU's, and a small-port Y-70 head and cam from Japan that doesn't let it rev very high but makes amazing mid-range torque, which is very good with the automatic transmission. I only get to the drag strip every few years but it does good there.The tech's were amazed at the flat torque line when I had it dyno'd. So keeping that setup seems good. On the other hand I could buy a L-28 and have more horsepower for about the same money. They could swap the Y-70 on a 280 block but something would need to be done to reduce the compression which is already high with the stock block. Using California 91 octane here. Think I want to stick with SU's, since I've learned a little about them, but I'm concerned they might be hard to tune with a higher-displacement engine. Not trying to build a race car, just fast and dependable for around town and the freeways.

Edited July 18, 2017 by Stanley

[siteunseen]

You could probably borrow a compression gauge from a chain parts store. That'd be my first step. Hope it's nothing serious. 

[Stanley]

13 minutes ago, siteunseen said:

You could probably borrow a compression gauge from a chain parts store. That'd be my first step. Hope it's nothing serious. 

I've been planning to refresh the engine since I bought the car. This seems like a good time to do it. I'd rather not even start the car and have possible debris moving around in there that could make the rebuild more expensive.

If I had a garage or if the management here didn't care if I worked on the car (beyond tune-ups) I might do something different.

 

 

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Edited July 18, 2017 by Stanley

[Zed Head]

How do the spark plugs look?  Easy to get to and might give you some clues.

One reason to do a little detective work early is because you might find that the engine is not "refreshable".  Hope that's not the case, but something like a big scratch n a bore can add a lot to the cost, to fix.  Better to know now than have the mechanic tell you in a couple of months.  Might make your L28 decision easier too.

[siteunseen]

I can tell you from my experience,  waaaay easier to rebuild a 2.8 than a 2.4. Parts are harder to get for a 240. Search for rings and a timing kit, gaskets too.

They all say put 2.8 parts on a 2.4 but I had trouble doing that. Took me a month to rebuild my 280, 3 months for the 240. 

But you do live in a little more Z friendly area.

[Stanley]

Should have thought to check the plugs but I'll do it tomorrow.

Been cleaning out the panel truck so I'll have something to drive. If the cops get behind me I won't be able to turn. No turn signals. Can't go on the freeway in the truck until I rebuild the front end. Steers like a boat over 50 mph. Runs good though.

[Captain Obvious]

Well I wouldn't be so quick to condemn the motor without a couple diagnostic tests first, especially in the middle of the driving season. Compression test would be high on my list. I'm still hoping it's not something serious.

I don't know how long it takes to burn through a piston, but I would hope you would have heard some pinging in order for that to happen.

[djwarner]

If there has been a catastrophic failure, It was probably only one cylinder and should be pretty easy to isolate by examining the plugs without running engine.

Obviously oil is getting into the cylinder(s) to be passed to the exhaust or a leak from a valve guide or cracked head. Clean plugs would point to the head.

Inspection cameras are getting to be fairly cheap. You might consider picking one up at Harbor Freight and examining the pistons through the sparkplug holes.