318IS to SE30 build thread

#21

A 91 318is will have the 55L tank, line early E30’s. Unlike the early cars the 318is has a single in-tank high pressure pump.

#22

@don, kinda messes you up even in 60m enduros if you get any fuel starve though.

#23

I pulled the subframe out if the 318 over the weekend. It’s a pita if you don’t remove the driveshaft from the rest of the car…

I took it all apart, installed my new subframe with the traded 3.73 LSD, H&R Race springs, and buttoned it all together.

#24

So i have that free m20 motor sitting in the shop waiting for me to change the gaskets, timing belt, water pump and seals. I don’t know the compression nor did I do a leak down test. The Guy I got it from said it came out of a good running car. he was planning to use it on his 2002.

Should I:
Option 1
just continue with my plan to freshen it up without tearing off the head, and drop it in my car? I’d be taking a chance by doing this, and investing some $$ in parts. I am running the risk of putting it in the car, and it being low on power… Then i’d have a problem… again, its only about $300 in parts.

Option 2
I do have enough m20 parts lying around to build another one…
Should I just throw this one in the car as is, and use my spares to build another motor? I’m on a budget, and can’t spend the usual 2k on a rebuild…

#25

Run a leak down test on the engine, since it need not be installed to do that test. Base what to do on those results.

#26

I assumed you need specialized equipment to do a leak-down test.

#27

All you need is an air compressor and leak down test tool.

#28

Basically you just need a leakdown tester and a reliable source of air pressure. There is a DIY on my website. I attempted to make the process sound as complicated as possible. http://www.gress.org/Home/Cars/TrackTales/track_tales.htm

The write up got really complicated because I struggled to understand how, in a theoretical sense, a leakdown test works. I also struggled with a leakdown tester that, well, didn’t work. A lot of the DIY takes you thru various experiments that help you figure out what you are doing.

Background you didn’t ask for. One of the things I’ve learned in this SpecE30 wrenching advanture is that diagnostic testing is fraught with hazard. The test might not actually test the variable you think it does. You might screw up the test and get a wrong results which costs you weeks and lots of $$. You might have more than one thing going and get a mix of variables that result in test chaos. There’s a lot of ways for diagnostic testing to hand your ass to you. Your only defense is to be as meticulous as possible and research everything.

A lot of people struggle with leakdown tests. It’s a lot harder to do a good leakdown than a compression test. You’ve got get the pistons to TDC, you’ve got to have predictable and stable air pressure (100psi makes it easier but you can compensate for a different supplyl pressure as long as it’s stable). Finally, you need to totally be in control of the leakdown tester. You need to know how to operate it and understand what it’s trying to tell you. My write up is long an involved because I played with these variables trying to figure out what I was doing.

If the engine tests good, pull #5 and #6 rod bearing and inspect their condition. If they look ok, put them back in with new rod bolts and install the motor. If they don’t look ok but the engine is sound either replace all the rod bearings, rod and main bearings. Bearings aren’t that expensive. Mind you these are shortcuts and you’re cutting corners. A full engine rebuild would be better.

IIRCC BavAuto has rod bolts for pretty cheap. Main bolts are reusable.

#29

That is some very good info Scott. Thanks

I have a spare junkyard motor laying around too and have similar concerns that Carlos has. I am going to do as you suggest one of these days.

Don

#30

Thanks for the advice Ranger.
The first thing im going to do is run a compression test. I’m going to put 12 volts to the starter, and use it to turn the motor. THis should help me see where i’m at. I’ll report the results.

#31

[quote=“silence” post=63926]Thanks for the advice Ranger.
The first thing im going to do is run a compression test. I’m going to put 12 volts to the starter, and use it to turn the motor. THis should help me see where i’m at. I’ll report the results.[/quote]
Be sure that your 12V source is as strong at the end of the test as it was in the beginning.

Things that can cause confusion…
Early tests do better than late tests because your power source gets tired.
Late tests do better than early tests because friction from all the testing is causing heat expansion which helps piston rings to seal.

You have to use your imagination on how to control for that kind of stuff. Like maybe a test order like…

Do each cylinder enough times to get the same value +/-3psi twice. Ideally, 1, 1, 2, 2, 3, 3 etc. Then do it in reverse, 6, 6, 5, 5, 4, 4 etc. Then average all the #'s and see if any of them suck.

This assumes all plugs are pulled and there is a charger on the batt keeping it topped up.

#32

Ok, so I pulled the plugs, grabbed a battery and the battery charger, and did a compression test on the motor that I acquired recently…
Results:
Test 1
1- 145
2- 140
3- 160
4- 168
5- 160
6- 98

Test 2
1- 160
2- 145
3- 161
4- 171
5- 172
6- 98

Test 3
2- 155
6- 100

Test 4 (cap full of oil in the cylinder)
2- 205
6- 174

This numbers are telling me that i need a bottom end rebuild… :frowning:

#33

Yep, a rebuild or a different motor.

#34

Good work on the testing. When you know the cause of a problem fixing it is no big deal. It’s when the cause is a mystery that one starts pulling out their hair. And wallet.

#35

Do you think i could be getting these low numbers because the motor has been sitting for a few years? Also, It was tested cold, so it should seal better at normal operating temperatures…
I’m considering throwing it in as is, and building another motor thats already apart.

Any thoughts on this?

#36

You have good reason to think that the engine is tired. Don’t put a tired engine into your car, you’ll just kick yourself next month when you have to do an entirely unnecessary engine swap. Do it right the first time.

#37

There are pros and cons to both. On one hand, Ranger is right. Swapping in a tired motor that may have more problems will just get you another swap before you want it. On the other hand, a rebuild costs money and the motor while not great is OK. OK will get you on the track running laps and learning race craft. While you’re doing that, build up another 2.5 the way you want and have it ready to go.

I spent a lot of money going the rebuild route before I got to the track with my car. In hind sight, I’m not sure I would have changed that. But that’s me. The practical approach would be to run what you have and start getting out there.

Besides, it’s not like there aren’t extra 2.5’s laying around between you and I that we could rebuild and have ready in no time…

#38

It’s looking like I may be trading my 91 318IS for 2 90 325i’s, one being a stock 4 door automatic, and the other a wrecked coupe with a salvage title, and lots of SE30 legal parts.
I’m planning on taking the Salvage car and building from there…

#39

The salvage car is here!!!
let the wrenching begin!

#40

Why the long face? :stuck_out_tongue: