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Discussion Starter #1
Ok, I know... I apologize in advance for repeating another thread on the subject.

2001 330Xi E46, Cold start is rough idle, lots of smoke and losing coolant. After 30 secs or so, idle smooths out, and smoke dissipates. Or if a little throttle is given, it smooths out as well. No coolant (seen) in oil, under cap, or dip stick. No wet spots in and around engine, or on ground. No smoke while driving, no over heating or even hot temps. Heat works too.

Last year I replaced radiator, expansion tank, a few hoses. All was good. AC wasn't working so took it to BMW for a fix, got it working and then this happened soon thereafter. (No relation of course).

180k+ got car 3 years ago, put the last 45k on it and a slew of typical maintenance work all done.

Haven't pulled plugs, or performed coolant pressurization or compression test. I wanted to get some insight before I dive in.

My thoughts are Head Gasket? I've rebuilt engines, so not a problem if that's what needs to be done. Would ask for any links pointing the way of course, lol, if that's the case.

Is my daily, so want to keep it going.

Thank you for your thoughts...
 

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A failed HG without an overheat is unusual, bug not unheard of.

A compression test is easy enough with a free tester borrowed from autozone. I suggest you do one just to rule it out.
 

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Ok, I know... I apologize in advance for repeating another thread on the subject.

2001 330Xi E46, Cold start is rough idle, lots of smoke and losing coolant. After 30 secs or so, idle smooths out, and smoke dissipates. Or if a little throttle is given, it smooths out as well. No coolant (seen) in oil, under cap, or dip stick. No wet spots in and around engine, or on ground. No smoke while driving, no over heating or even hot temps. Heat works too.

Last year I replaced radiator, expansion tank, a few hoses. All was good. AC wasn't working so took it to BMW for a fix, got it working and then this happened soon thereafter. (No relation of course).

180k+ got car 3 years ago, put the last 45k on it and a slew of typical maintenance work all done.

Haven't pulled plugs, or performed coolant pressurization or compression test. I wanted to get some insight before I dive in.

My thoughts are Head Gasket? I've rebuilt engines, so not a problem if that's what needs to be done. Would ask for any links pointing the way of course, lol, if that's the case.

Is my daily, so want to keep it going.

Thank you for your thoughts...
"No coolant (seen) in oil, under cap, or dip stick. No wet spots in and around engine, or on ground."

Sounds like my first failed ET. But you say it's only 12 month old. That's a mystery. Probably best to bite the bullet and do a compression test first. If it's good then yippee. If it's not then anything else is a waste of time.
 

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Whoa, slow down there horsie.

Could it be a head gasket, sure. What if it's dirty injectors leaking down fuel into a couple of cylinders and you yank the cylinder head off...?

I'd suggest some testing is in order before you attack any repairs.

Get a higher level scanner where you can see not only fault codes but number/times/mileage any faults occur.
Live data is a HUGE plus.

Hook up a fuel pressure tester to a warm engine, start & shut off. Watch for large pressure drop after an hour or two. If it does, could very well be leaking (drip down) injectors giving rise to your issue.
 

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Whoa, slow down there horsie.

Could it be a head gasket, sure. What if it's dirty injectors leaking down fuel into a couple of cylinders and you yank the cylinder head off...?

I'd suggest some testing is in order before you attack any repairs.

Get a higher level scanner where you can see not only fault codes but number/times/mileage any faults occur.
Live data is a HUGE plus.

Hook up a fuel pressure tester to a warm engine, start & shut off. Watch for large pressure drop after an hour or two. If it does, could very well be leaking (drip down) injectors giving rise to your issue.
Where does the coolant loss fit into your theory?
 

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Discussion Starter #6 (Edited)
Thanks for the responses, I have a code scanner, no codes though. I also have a compression test kit, so that's an easy one too, just wanted to pick brains before I rolled up my sleeves. Rough idle on injectors, maybe, but I'm thinking maybe coil packs because I haven't changed them and mileage is unknown on them, but no misfires are present, so that issue is a little befuddling too, unless it's HG which could cause the thought idle with coolant in cyclinder. Wouldn't the O2's be off then? Dump fuel or pull fuel based on exhaust? Hmmmm? Anyways...

Coolant is scary, all I keep thinking is I'll pull a plug and it'll be wet, dripping blue, lol. I hope not. Puff of smoke has gotten larger on start, is why I keep thinking HG.

I'll do compression test asap and update the thread.

Thanks again :)
 

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Discussion Starter #8 (Edited)
Puff of smoke on cold starts could be valve guides, if the smoke is blue. Condensation and coolant would be white, excess fuel would be black. Coolant pressure test might be in order.
Thank you for the suggestion, but the loss of coolant is the issue and thereby pretty much assures the smoke is coolant. The culprit is the question.

I'm not losing oil, or getting misfires from undetonated fuel which would cause black smoke. It's puffy white... ;) Valve guides are interesting in any event and if so, I'm sure would also include a visible show on plugs when removed. Could it then also lend to rough start as oil is burnt off plugs...? But again, wouldn't explain the loss of coolant with no other visible leaks evident. Which brings my thoughts back to HG.

Just deductive reasoning... Should be fairly nice this weekend which will allow me to dig in. Compression test first, if good, then leak down or I'll rent the coolant pressure test kit and go from there.

But to assuage my fears... How bad is a HG change on the E46/M54 engine? Is HG fail typical or is it the head itself? Again, no overheating issues exist (since I've owned it). I've seen a lot of mention on the heads which of course is a concern. And with no untypical oil consumption for it's age, there was some, but replacing all the CCV fixed that. Is a full rebuild even worth it, or just replace HG and run it until fail? Swap engine later if it happens? These are the scenarios running in my brain, lol.
 

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Typical is a warped head due to an overheat..Doesn't sound like your situation. I have seen head gaskets fail without an overheat. Have also seen cracked heads. But both are uncommon.

Many people simply replace engines when faced with a head gasket. For most DIY'ers it is easier and about the same money, with less risk of failure. Depending on circumstances, I might do that, but I would then try to save the bad engine. I happen to think we might soon find it more difficult to source good M54 engines..probably not for a few years. I have 2-3 refreshed M54's ready to go into a nice car (X3, X5, E46, E39) that has overheated.

I have done several head gaskets, both in car (E39/E53) and on engine stands. Not too bad. All were successful.
- I always time-sert the block - whether it overheated or not - I own time-sert kit 1090 and it's a breeze.
- I pull the cams and timing gear using methods on shown on youtube (50;s kid)
- Getting the head/valves checked and res-surfaced by a machinist is first order of business. If the head can be saved (warped less than 12 thousandths), machining costs run $200-800 depending - I just had 3 badly warped heads straightened in an oven and then resurfaced. $800 for head repair does not make sense.
- If machinist has taken off 6 thou or less to re-surface, I use thinner (0.70mm) head gasket. If more, I use the thicker gasket (1.00mm)
- Don't buy the cheapest head gasket and head bolts. Aftermarket is fine though
- If I have the engine on the stand, I will likely also replace piston rings w/ upgraded M54 Mahle rings too..That way I have a refreshed engine that should not burn oil. This means new conn-rod bearings and conn-rod bolts . Yes this is mission creep.
- I re-time the engine using 50's kid excellent timing video and my timing tools
 

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Discussion Starter #12 (Edited)
Effduration, thank you for the wealth of information. Yes the HG job doesn't scare me, and I understand the value of going the extra distance (refresh). Body and interior is in pretty good shape and I've done a lot of other maintenance and upgrades that should give me a few more years at least. So...

Where are you located and what is the avg cost of salvage engine vs the parts for refresh including heads? Exclusive of labor of course, just looking to get an idea...

Car has sat a few days, started it today for a quick ride. Not too much smoke, low coolant light came on, rough start. Drove about 5 miles, sat and idled and SEL came on. A few codes, not unexpected...
P300
P1343
P1345
P0174

Compression test this weekend for sure!
 

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I am in MA and a salvage M54 3.0 engine is $500 to $1000. The cheapest way is to find a running parts car with this engine, test it for compression, buy it and part it out, keeping engine. I've sold a battery and a single spare wheel and got my $$ back before.

If you rebuild, the cost to machine head, new bolts, new head gasket, rent timing and time-sert tools is $350-$600. New piston rings, conn-rod bearings and bolts +$250

whether you buy a salvage engine or rebuild your own, you will want to refresh all the gaskets, seals, and most of the cooling components, including the hard plastic pipes under the intake. You will need new exhaust hardware and a few other things. This is $500

So

Replace Head gasket- only rebuild is $350-600 + 500 = $850 - $1100
Replace Head gasket + piston rings rebuild is $600 - $850 +500 = $1100-$1350

buy a salvage engine and freshen is $500-$1000 + 500 = $1000 -$1500
 

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My wife overheated the our 2000 323iT twice: first time a cracked head and second time cracked head and pulled head bolts threads off the block. I just bought good used heads on ebay to replace and Timesert all head bolts threads. Everything else is good tight still running great with 10K oil change interval with zero top off oil needed. Why replace a whole engine if just head or gasket needs replaced?
VANOS timing without special tool.
 

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Discussion Starter #15
I know it's been a while, but finally had time to start getting going on this.

Seems the coolant loss has lessened a bit as temps (weather) increased. Haven't really driven it, short trips to store and such, just to keep fuids moving. Each time had to add coolant because I'd check and was lower than when I last topped it off. Had to add about a little more than an ounce each time (2x).

But I finally got to the engine. Pulled plugs, they looked alright, nothing really standing out. Replaced them anyways.

Warmed engine up, took it for short spin, put it up on ramps, and did the compression tests... Didn't do cold test, or wet. Went straight to go! Did tests 2x to confirm numbers...

Cylinders PSI
1-125
2-110
3-138
4-140
5-145
6-150

So cylinders 1 & 2 aren't looking good. Add to it, those two plugs looked "wet" when pulled, smelled faintly like coolant, but definitely small droplets on the new plugs electrodes for those cylinders. Yes, DME relay pulled so couldn't be gas, and no gas smell anyways ;)

Could do a coolant system pressure test, but I'm pretty sure it's the HG. Engine is running really rough now too until warmed up. Is driveable, but worried about prolonged use and possible worse damage.

So have to make some choices... Will check head bolts by re-torquing them tomorrow, go from there. If they're good, I might just do the head gasket... Boy oh boy...!?

Just wanted to update the thread as I've not done so. Again, appreciate all input.
 

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Even if the head bolts all hold torque, I think many would recommend the block be timeserted regardless.

Does the cooling system pressurize quickly after a cold start by any chance? If the cyclinder compression is leaking into the cooling system it would pressurize the upper radiator hose quickly before the coolant has a chance to warm up. On cold engine, open expansion tank cap to equalize pressure then close and start engine. In about a minute check upper rad hose for pressure. In this scenario you would also loose cabin heat as the heater core fills with air.
 

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I have heard and seen enough...history of an overheat, loss of coolant and big differences in psi on a compression test. You either need to install a used engine OR do a head gasket and possibly some valve work on the head you have. There is chance (25% I think) that head would be too far warped to use. A machinist will tell you this for sure, but if it is warped more than 12 thousandths, it is pretty much unusable.

Estimated costs for the various options are above... A used engine might be a little quicker if time is important.

Forget about torquing head bolts..that was a test BMW & their dealers came up with to sell you a new engine. Just plan on time-serting your block if you pull the head off.
 

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Discussion Starter #18 (Edited)
Haven't checked that, but haven't noticed any difference with heat, although I haven't driven it much either as noted. I'll take a look tomorrow, check hoses too, they're all fairly new as I replaced radiator, exp tank and a few hoses last year.

Effduration thank you for your valuable insight and experience!

Not afraid of work, as noted, I've done engine work on my other cars, just unfamiliar with the BMW variety. Have a machinist I've used for head work on my other engine build. If HG I would reseat valves, check springs, replace seals, etc. Any gains from porting? Also, I'm going to need to put a list together lol... What about Vanos and chain, other gaskets or seals? Replace too? Or just tensioner and possibly solenoids? Shooting from the hip now as I've not really jumped into this pool yet. Replaced the CCV last year too, what else would be smart while it's all apart? And know as I'm rambling I can see why maybe an engine swap might be quicker, less involved. Just wouldn't want to get an engine and have same problem later. Is a conundrum, lol. Shipwrights disease grows quickly, lol...
 

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Discussion Starter #19 (Edited)
Done a lot of searching, not many engines out there that I'd jump on. Most are stripped, not all verify mileage, and those that do and have been compression tested or running are all over $1k to $1.5k which is crazy IMO... So it's a crapshoot really!

Buy a used engine and deal with the same issue in time...? Most are around 125+k mileage, so no thank you. If I had another engine, I would in all probability tear it down and do the same to it, and more, make it bulletproof so to say. So the only advantage would be to keep the car in operation while doing the engine work. I have other cars so I don't think that's necessary. Can pull the head and go from there.
 

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Discussion Starter #20
Sorry for not updating as I've yet to do the head gasket, lol. But it's going to be done this month. Car has been neglected, haven't even swapped winter tires off her I've not driven her. With Covid and all... Even the battery died on an AGM battery no less.

Anyways, just figured to drop a line, keep thread open. Check engines again, nothing really low mileage I'd jump at that's avay, so it'll be the hard road, pull the head and do the work.

One question would be what else to do while in there? Almost everything has been done already such as VCG, OFHG, 2nd Air Pump, CVC, etc ... So thinking engine mounts while everything is open/accessible, but can't think of much else.

Anyways... Gotta make some lists, parts, tools, etc. ;)
 
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