Engine Replacement Options on a Budget (Under $1K)

[MattL]

My '76 smokes like a chimney. Mostly on acceleration, but also sometimes on decel. Plenty of smoke under the oil cap. I haven't done a compression test yet, but given these symptoms, I'm pretty confident the rings are gone at a minimum. I'd rather not go the rebuild route, simply because I wouldn't want to pass up the opportunity to breathe on the engine a bit (higher compression, if possible on the E21 2.0; mild cam, etc.), but don't have nearly enough cash to pay someone to do it right or the skills to do it myself. This seems like the kind of thing I would do a really good job of screwing up. So, I think a replacement is probably in order. 

 

I've read all kinds of FAQ posts on swap candidates, but mostly from a while ago, in the "more power" category, in price ranges well above my budget. Although I'd like to get something that's improvable/upgradeable, budget and reliability are the biggest factors for me at the moment. Is a straight 2.0L M10 swap still the best option? What about a 1.8? 

 

Apologies if this has been covered ad nauseum and I somehow missed it. 

 

Thanks,

MattL

[Jimmy]

1 minute ago, MattL said:

My '76 smokes like a chimney. Mostly on acceleration, but also sometimes on decel. Plenty of smoke under the oil cap. I haven't done a compression test yet, but given these symptoms, I'm pretty confident the rings are gone at a minimum. I'd rather not go the rebuild route, simply because I wouldn't want to pass up the opportunity to breathe on the engine a bit (higher compression, if possible on the E21 2.0; mild cam, etc.), but don't have nearly enough cash to pay someone to do it right or the skills to do it myself. This seems like the kind of thing I would do a really good job of screwing up. So, I think a replacement is probably in order. 

 

I've read all kinds of FAQ posts on swap candidates, but mostly from a while ago, in the "more power" category, in price ranges well above my budget. Although I'd like to get something that's improvable/upgradeable, budget and reliability are the biggest factors for me at the moment. Is a straight 2.0L M10 swap still the best option? What about a 1.8? 

 

Apologies if this has been covered ad nauseum and I somehow missed it. 

 

Thanks,

MattL

 

Have a compression/leakdown test done. You may just need the head rebuilt, valve/guide wear is common. When the head is off the cylinders can be inspected and you can decide to proceed with the fix or source a swap. You run the risk of needing to do the same work to a used engine, especially in your target price range.

 

Wherever you end up, keep in mind cheap oil and a poor state of tune will accelerate wear due to a combination of poorly adjusted valves, carb, or timing causing excessive combustion heat, dilution of oil with fuel from running too rich, or generally poor lubrication. So a motor that "runs fine" now will not continue to do so over the long term if it doesn't get straightened out by someone who knows what they are doing.

[MattL]

1 hour ago, Jimmy said:

 

Have a compression/leakdown test done. You may just need the head rebuilt, valve/guide wear is common. When the head is off the cylinders can be inspected and you can decide to proceed with the fix or source a swap. You run the risk of needing to do the same work to a used engine, especially in your target price range.

 

Wherever you end up, keep in mind cheap oil and a poor state of tune will accelerate wear due to a combination of poorly adjusted valves, carb, or timing causing excessive combustion heat, dilution of oil with fuel from running too rich, or generally poor lubrication. So a motor that "runs fine" now will not continue to do so over the long term if it doesn't get straightened out by someone who knows what they are doing.

 

Thanks for the advice, Jimmy. This, especially, is a really good point that I've only halfway considered. Whatever I end up doing, I'll be sure to get things tuned up correctly.

 

I'll get the compression/leakdown test done and proceed from there. If I don't need to do a rebuild of the block, all the better. If it DOES turn out to be the piston rings, though, there's no way to avoid pulling out the engine for a rebuild, right? That's the scenario where the While-I'm-At-Its seem like they'd be unavoidable and expensive. 

 

If I were to end up going the replacement route, are there any M10s or other BMW motors of the era that I should NOT consider given a choice? Ones that have inferior reliability/swapability/power, etc.? 

[Mike Self]

Quick rule of thumb on an M10 (and other engines, but especially M10s):  smoke on acceleration = worn rings; smoke on deceleration (closed throttle, coasting in gear) = worn valve guides and/or stem seals.  

 

Rings mean delving into the engine...$$$; valve guides/stem seals, a lot less expensive, especially if you R&R the head yourself.  But be advised that when you do the head, it'll make those old rings the new weak point, and then they'll start to cause smoke.  There just ain't no cheap way out!

 

Presume you're currently using 20W-50 oil, and are watching your consumption to make sure it's getting high...

 

mike

[Jimmy]

I would agree with the clarification that when a closed throttle causes oil to be sucked past the valve stems/seals you can get a huge amount of smoke when you transition back to on-throttle. If upon acceleration the smoke gets worse or does not get better, rings are likely. If it puffs a lot initially and goes away with the throttle constant, valves/head are likely.

[evil02]

What color is the smoke? Different colors could mean different things. I mean, are you burning oil, gas or coolant?

[MattL]

Thanks, Mike. That's what my understanding was. The bulk of the smoke is definitely on acceleration. The smoke itself doesn't bother me, of course, it's those dollar signs that follow it. ?

 

Correct: 20W 50. I also have a bona fide oil leak somewhere, so it's difficult to estimate the consumption attributable to the rings (or whatever). I don't travel long distances in the 2002, but I carry an extra quart with me in the car, just in case I do run low on the road. 

[evil02]

I would say, if it is NOT your daily driver, park it and save money up to fix it. That way you just do it once. 

 

If it is your main car, just keep adding oil until something blows up.. all the while, save up money to fix it right.

[xr4tic]

How much smoke are we talking about?

 

If it's a lot, then find yourself a good running used engine, drop that in, and then save money to rebuild your old one.

 

If it's just a little, then I say save your money and keep driving it until you can afford a proper rebuild.

 

If the rings are worn, then there's a good chance your cylinders are now out of spec, requiring new pistons and a re-bore.  That alone will kill your $1k budget.

[TobyB]

Quote

 I mean, are you burning oil, brake fluid, gas or coolant?

 

 

Post up a WTB for a solid engine for $1k and see what surfaces.

 

Critically, WHERE ARE YOU?  Lots of us have junk in storage that you might get off us for cheap...

 

I agree, tune what you have to the best it can be, and see.

 

I HAVE put engines in that smoked like crazy at first, but with a few

track days, got better as seals softened, rings cleaned up, etc etc...

 

t

 

[MattL]

Thanks for all the replies, everyone. To answer your questions:

 

This is not my daily driver. It’s my long-dreamed of fun/project car. (That’s really why my budget is what it is: I am lucky enough to have this car in addition to the family, the mortgage, and any number of other expenses that aren’t as optional.) ?

 

The smoke is blue/gray and it’s not noticeable until I really put my foot down. At that point, it’s pretty substantial. It’s not really visible through the rear view mirror, but “Big puff” is how people following behind me have put it. When I test it in the driveway, it seems to take a rev of at least 3500-4000 rpms to make it appear. Floored, the blue is sometimes accompanied by a little black, which I take to be a completely different, fuel delivery or ignition issue. I haven’t smelled that nasty sweet burning coolant smell, but the car always smells like burning oil after a drive. 

 

I’m located in New Jersey, just outside Philadelphia. 

 

Once I make a big enough dent in the Honey Do list to allow me some garage time, I’ll get the comp test done. 

 

Again, thanks for all the input, guidance, and help. This community is incredible. 

[Jimmy]

If it's not visible in the rear view, how bad could it be? ?

Are you running the stock air filter housing and is the breather hose from your valve cover still connected to it? 

I'm also curious to know how your spark plugs look and if all four are in comparable condition, don't run out and pull them expecting some absolute diagnosis, but they certainly can add insight as to how things are going.

The black smoke at wide open throttle is from extra fuel not burning completely due to full throttle enrichment. I can't say that it doesn't need adjusting, but a full throttle enrichment "mode" is a fail-safe that prevents sustained load from resulting in a burned up engine, so a minor amount of black smoke at full throttle is normal. It shouldn't look like a diesel though. Don't monkey with the carb just yet, it won't fix the blue-grey smoke. 

[iinca]

 

Yank that tired old motor and set it aside for a possible rebuild.

 

..AND look in the Parts for Sale.

Good solid engines are always popping up in there...also do the WTB as suggested above. 

Edited December 2, 2018 by iinca

[TobyB]

Quote

My '76 smokes like a chimney. 

 

BUT

 

 It’s not really visible through the rear view mirror,

 

DON'T WORRY ABOUT IT!!!

 

I'm serious.  If this is a fun play car, spend your time and money getting all the things inside done that you want to.

Make it just the way you want it, and critically, budget for and buy all the cosmetic things you want, NOW, as a priority.

 

Drive it.  Use a thick oil, tune it, buy carb(s) you want, convert it to EFI, get it painted, detailed, put in that paisley headliner 

in orange that you've always dreamed of.  

 

Work on it as therapy, when you have free time, but only when it's fun.

 

Do make sure it's not sucking oil out the breather and back into the carb.

 

DO keep your eyes open for a spare motor to build, but ONLY if it's a real deal- a $100 core, a $500 fresh shortblock, a $250 head

that's just been gone through.  That sorta thing.

 

WHEN it's time, then you can do the engine.

 

BECAUSE that's not that much smoke for a 2002.  

REALLY.

Modern cars don't smoke.  

Fresh M10's only smoke a little.

Well- used but still sound M10s can smoke A LOT, use less than 

a quart every thousand miles, and still make good power.

For at least a decade, INCLUDING track days.

 

You still have a decent engine.  

 

So go drive it!!!

 

t

 

[MattL]

Now those are some marching orders I can follow, Toby. Roger, wilco!

 

I probably am over-careful with this car, maybe bordering on hypochondria (hypo-car-ndria?). I trust this forum and all of you on it to chill me out a bit when I need it. But I (and my girls, too) have really fallen in love with the car in a short time and I don't want to hurt it. 

 

I do still have the breather hose connected, but I've got a baffled catch-can setup with a filter waiting to be installed. You're right that I probably don't have a good understanding of what constitutes "a lot" of smoke from these engines, but the smoke under the oil cap and the fact that everybody who drives behind me comments on it rang alarm bells for me. Jimmy, I'll pull the plugs in the course of the comp test, so I'll update when that's done. 

 

Once again, thank you to everyone for your input. Here's a shot of the car's 2nd biggest fans (tied):