>rough idle >odd sounding exhaust note under load >vibrating power under heavy load >knocks if you let off throttle too fast >sounds like bearing noise when loaded right after cold start
I think my compression is fucked on at least one cylinder, and I'm pretty sure my crank bearings are toasted. Head is freshly rebuilt, head gasket is new, timing belt is new, and everything that could possibly create an intake leak is new.
The only things I haven't done are clean my injectors and run an actual compression test. Running a test in the morning and I've got a can of brake cleaner and a 9 volt battery ready for action.
I can't afford to have someone else do a bottom end rebuild. I'm terrified that my crank is cracked/bent or I have a spun bearing. I really suspect that the PO (stancefag) hooned a little too hard, smashed the oil pan, and then ran it dry just long enough to fuck the bottom end, but not long enough to seize it. Then fixed the pan (this is visible), filled it up with oil, and threw it on CL.
So you did a top end rebuild, and just figured the 20+ year bottom end was all fine and dandy? Or was that the PO that claimed that?
Regardless how old are the engine mounts? How old are the intake boots/vacuum lines? ICV and MAF been cleaned recently? whats the condition of the rest of your fuel and ignition system? Is it possibly getting fuel starved? does the knocking sound like rod knock or Pre ignition knock? those are all things that should be asked.
Joshua Hughes
M20B27.
It's a 1984, so it's 33 years old. It turns 34 in August.
Engine mounts are original. Intake boot is new and every vacuum line was replaced with a silicon hose kit and all new hose clamps. ICV has been blasted with piss, and I cleaned the carbon track of the AFM. New fuel pressure regulator, but fuel pump is unknown. Plugs are new. Cap and rotor look fine.
It's pre-ignition knock. There's nothing resembling rod knock. It doesn't happen all the time, but you can make it happen if you come off the throttle too fast.
>figured the bottom end would be fine I'm not shocked that it might be hooped. Since it hasn't grenaded yet, I guess it can still be fixed if it is gone.
If compression checks out fine, I will then check the fuel pressure.
Oliver Diaz
Just remember you need 3 things for proper detonation.
Spark, Fuel/Air Mix, and Compression.
If you've confirmed the first two then ...
Jordan Morales
A few things, you might have two fuel pumps. I would have a feeling if its something mechanically wrong with the bottom end it would be making much worse noises than pre-ignition knock. Most instances with pre-ignition knock are time or fuel starvation related.
Does your model have an O2 sensor? That would cause problem with the fuel mapping which would affect both and idle and the rev range and Insofar as I know the early E30's have limited CEL codes so a bad O2 sensor wouldn't show up as a CEL.
Overall that, seeing as how you have the b27, a head swap to a 2.5 head, or motor might be a option to consider if it is fact the bottom end.
Justin Rogers
Oh one other thing, when the head was redone, was the timing done correctly?
Isaac Peterson
I'm fairly sure there's just one in-tank pump, but I could be wrong.
>codes lol
The only lights on the dash are a "something's fucked" light, oil pressure light, battery light (which, it turns out, kills your whole charging system if it burns out), and some other brake-related lights. There is a head unit that has stuff like brake fluid level and coolant level, which is cool.
There is an O2 sensor, and I should probably replace that too. On the B27s, the sensor is under the car for some reason though, and I shamefully admit that I have a jack but I don't know how to jack it up and put it on stands. But yes, I should replace that. The ECU does detect when the O2 sensor goes though. Good thought.
>2.5 head swap Funny you mention that. I have an 885 head that I pulled from a yard. I about shat when it came up online. Literally took a day off of work to go snag it. I was going to do a head swap either way, because the 2.7 bottom end with the 2.5 head is basically a cheap stroked out M20.
My end plan for this car was to have an 885 head on the B27 short block, a standalone ECU, and ITBs rigged from two Triumph Daytona throttle body assemblies. If I end up having to have the bottom rebuilt, I think you can go all the way to 3.0 L if you bore the shit out of it.
>timing The top end was professionally rebuilt. New tensioner and water pump at the same time.
So, in order: >compression test >fuel pressure test >fuel pump(s) >O2 sensor >injector cleaning >motor mounts
I know what I'm doing with my 4th I guess. I will report.
Jordan Sullivan
>Head is freshly rebuilt yep i made the same mistake, when your doing heads you should also do a bottom end rebuild while its off, at least rings and shiet
Brandon Long
Nice quads. If you can get ahold of peake scanner or knock off peake scanner (bav auto has one that's fairly cheap) plus the OBD II to BMW circular connector, it would at least give you a direction to head towards, even if its vague.
I have poor idling and hesitation with my 88 325i and its registering as emissions/O2 not getting proper signal, related which probably means I have a vacuum leak or the O2 has shit the bed.
Daniel Baker
>falling for the bimma trap
Joshua Bell
>vacuum leak or the O2 has shit the bed Both of those are super easy fixes though.
Spring $100 for a silicon hose kit. Worth it.
I kind of want to pull my engine anyway just to clean everything. The block is bare cast iron, which bothers me too. Want to paint it.
I don't know how much I trust a 34 year old rear main seal either. I think it's time.
>OBD adapter intredasting...
I bought it because it weighs 2500 pounds.
Justin Myers
He who do not owneth the GOD MASHINE shalt not talk upon the GOD MASHINE, for it is blasfeme and thou shalt be struck down upon.
Luke Edwards
I know they're easy fixes I was just pointing out that the scanners at least give you an idea of possibly what's causing your problems.
Isaiah Campbell
Pretty much all fuel injected BMWs from the 80s have a low pressure pump in the tank that's extremely prone to fail, as well as a larger bosch pump outside the tank. Listen to the port where the in tank fuel pump assembly meets the body. It's in the trunk on e28s, not sure about e30s. If it sounds bad you have 3 options. 1. Buy the $300 OEM fuel pump assembly 2. Buy a ~$20 pump from a chevy vega and attach it to your assembly 3. Buy a single aftermarket high power in tank pump to replace both pumps. Normally cars with a bad pump will stall out and run badly at all rpms and choke super hard at high rpms. Sounds like it could be your issue
Kevin Walker
Sperg alert: Not that it affects OP but late models only have the in tank pump
Hudson Wilson
You're right. I apparently have two fuel pumps. E30's have the in-tank pump accessed under the back seat. >chevy vega I don't know why this made me laugh.
Does the external Bosch pump not generally fail? If I am having fuel pressure issues, will a fuel pressure test reveal them? What does a failing pump sound like?
>high power in-tank pump This seems like a good option. Having two pumps just seems weird to me. If is correct, do you wire the new Hulk pump to the original in-tank harness, or to the external pump?
I have a high power pump in place of both of mine in my e28. Don't remember what brand it is, but you'll need to get your fuel pump assembly modified. There are people who sell pre modified ones out there. The bosch ones are generally more durable and also reasonably priced. A bad pump will generally make a high pitched squealing noise. youtu.be/wM4sbK5JyXM
Joseph Robinson
forgot to mention that both pumps are on the same fuse and you should be able to pull decent amps from the stock in tank plug
Oliver Phillips
Yep, that's a familiar noise. I always thought it was just supposed to sound like that.
>both pumps are on the same fuse I wonder if they're on the same relay too.
I really don't feel like buying two fuel pumps though, and I'm seeing things like the TRE/Walbro 255 for $70 new. I'm fine with redoing a fuel line (mine is actually cracking a little at the FPR anyway).
But this is only an issue if I'm actually having fuel pressure problems, right? Which I can only really know if I do a test with a gauge, right?
Henry Gomez
Do you live in texas
Noah Williams
Test it with a gauge. You can short out the relay to force them on. I have the TRE one, now I remember. It works well with my M30, so I don't see any risk running it on a M20
Wyatt Harris
I'll do that in the morning. After compression testing, which could make all of this moot to begin with.
Even if it's fine, I kind of want to update it to a single pump. Thanks for the help.
What if I did? inb4 >your car is too loud >you cut me off in traffic fuck you >ricer faggot
Austin Ross
Godspeed to you OP. Here's to hoping its a simple fix. I just went through something similar with my rally car. Awful idle and hesitation under low speed /high load conditions. Started with coils/wires/plugs then did a compression check all being ok. Turns out it was a severely clogged injector (pic related). It looks like it's on your to do list so you've got a good plan of action. I don't have any personal experience with BMW's so I'll leave the specifics up to those who have already responded.
Jose Evans
I'll post in this thread what I learn tomorrow if it's still up. If it's archived by then, I'll start a new one.
Robert Bosch's ghost is on my side.
Ethan Rogers
postage bump
Jace Hill
Bump
Jose Lopez
Numbers are in! Service limits say that the lowest cylinder should be 60% or more of the highest cylinder. Google says that a new M20 should hit around 150 PSI. These might be a little off because I suspect that I wasn't doing the wet test correctly (I think my spray can was running dry).
Highest was 200 PSI. 60% of 200 PSI is 120 PSI, which I'm safely within, and all cylinders exceed the compression of what I'm reading a new engine is supposed to have. But my interpretation is that this isn't without problems.
Cylinder 1 is still low. Since the wet and dry tests are so close, I suspect that one of the valves is not seating fully. Cylinder 6 has the largest difference between wet and dry, so I suspect that it has the most worn piston rings, but it still appears to be well within service limits.
Following the test, I put everything back together, torqued my spark plugs, and dumped a can of injector cleaner into my gas tank. I took it for a little hoon around a few blocks, and it's running mysteriously better. I unplugged the battery for the test, which would have reset the ECU, meaning that all of the fuel maps are fresh.
Going forward: I already ordered a high pressure in-tank fuel pump (a TRE 255) and will be updating the transfer to in-line arrangement. Maybe in the future I will run a surge tank just for giggles. I can't readily replace the O2 sensor because I have no safe way of getting under the car. I'm going to do a fuel pressure test either way.
Tyler Gutierrez
Sweet.
Seriously though you need to break down and get a set of stands and a Jack, if your car was owned by a stance faggot I would really be worried about fuckery with the suspension. But all in due time.
Brody Roberts
For the record, this engine has at least 160,000 miles on it. That's what's on the clock, and the odometer was broken when it landed in my driveway. I suspect it's closer to 200,000 miles. It's overheated at least once.
Coming back around: >compression test Passed. >fuel pressure test Working on it. >fuel pump(s) Waiting on the post. >O2 sensor Next on the list. >injector cleaning Cleaner in the tank. I can't decide if I want to pull them off the rail and clean them individually. >motor mounts I don't think I can do this myself. I don't have a hoist or a garage or friends who do.
Also, just because my compression is fine does not mean that the bottom end isn't on its way out. What do I listen and feel for to assess crank and rod bearing condition?
David Moore
I have a jack and I can afford stands, but I don't know how to use them, and using those things incorrectly seems like a really fast way to either bend something that you don't want to bend, or end up dead.
Tyler Miller
Thinking about this again, is it possible that when my head got resurfaced, my compression ratio was increased this dramatically? I used an OEM thickness head gasket. Obviously compression is a good thing, but this being so far over spec tells me that this is not the factory CR. 35% over spec on 5 out of 6 cylinders isn't an anomaly. Something's off. I did also use a steel head gasket
But, that isn't the most important thing in the world because I'm eventually planning to replace the head anyway. What this test told me is that my bottom end compression is still well within service limits.
Ethan Watson
You bought this car this year right. I remember you. Want some of my parts? It's just taking up space
Ryder Miller
You have a parts car or something? I'll take anything I can get.
Justin Ramirez
postage bump
Colton Evans
the only way to properly assess rods and crank is ye olde plastigage
Christian Ortiz
They're not that hard to use, just don't use the factory jack that came with the car to jack it up to service it and only use a floor jack to raise it up immediately put jack stands under the car before servicing, Jack stands have a ratcheting system that keeps them from collapsing.
Use a floor jack, and on e30 there are 5 points you can jack under, the four factory jack points points on the underside of the skirts, under the differential and under the front cross member under the engine.
My e30 is on lowering springs so I use two floor jacks one under the factory jack point, jacking it up high enough get the second jack under the front cross member or differential to jack it the rest of the way up.
Once I have it at a reasonable height I put two jackstands under the factory points and slowly let the car back down onto the jackstands.
Tyler Davis
I know, I need to do it. I at least need to know how. Do you jack it up by the diff itself or where the diff attaches? Are the factory jack points where you see the floor pan come into the quarter panel?
Regardless, the motor mounts are 100% an issue.
I really need a garage more than anything. I need a place where I can sit the car while I pull the engine out, put it on a stand, do to it, de-rust and paint the block, and figure out specifically how stancefagged it actually is.
To any stancefags reading, please. Please. Stop.
Bentley Young
not him but i have an e30 in texas, what parts you got bb
Joshua Price
now you're making me feel bad for not painting the block in my project car it's in already
