just purchased a 88 M5

[texasporschedude]

I am new to this forum, I purchased a 1988 M5 this past weekend. Very clean car, but very high miles.(225,000) Not sure where to start. A lot of records came with it. It it idles rough and lean. yet above 2500 rpm it seems solid. Any ideas where to start?

[Duke]

Welcome.


Search this forum. Read, read and then read more.

Look for records that the timing chain and tensioners have been replaced. If not, STOP DRIVING THE CAR, and replace the timing chain and tensioners......do this yesterday.

[mooseheadm5]

In addition, I suggest having your injectors "rebuilt" while you are messing with the timing chain. A popular place to do this is http://www.cruzinperformance.com/
Check the condition of all the rubber boots since cracks can cause a lean condition. If you didn't have a compression and leak down test done before purchase, now is a good time.

[texasporschedude]

Thanks for the information. I went through a stack of records, not timing belt replacement. The 2nd owner appears to have kept all his records. Kind of crazy it would not be changed by know. I ordered my repair manual so I will be tearing it down soon.

[Duke]

I went through a stack of records, not timing belt replacement.

Remember, its a chain.

Don't drive the car until it is replaced. I would not even start it. Others have destroyed their engines with half the miles you have on yours.

Read these -

http://www.mye28.com/viewtopic.php?t=18 ... ming+chain

http://www.mye28.com/viewtopic.php?t=27 ... ming+chain

[Philo]

Welcome !

You car is low mileage compared to mine at 320k.

Regarding the rough idle, I've found that these engines idle the best at around 13.5-1 AFR however the US cars are set to 14.7-1. As a test try unplugging your 02 sensor and you'll see what I mean. The car will idle better and the hesitations at part throttle below 3500 RPM will be gone. You can chip the car to alter the AF map.., or just live with the lumpy idle. Mine was really bad when I ran the AFM.., but changed to an after market engine management and run 10 degrees advance at idle and a 13.8-1 AFR. Much much better idle The only other thing you can do to smooth out the idle is bring the idle up to 950 RPM.

What I'd do first is the compression test and leak-down.., and if that looks good then start with the basics, tune up, valve adjustment, make sure you don't have any air leaks, adjust the throttle bodies, and AFM idle setting (adjustment screw thingy).

Maybe even before doing engine stuff check the brakes, control arm rubber, suspension.... make sure the car is safe. Because you WILL want to take her up to 100mph plus. Trust me. The first time a ricer is being a dick your gonna dump the pedal. Edit.., on the way home a kid in a Mazda3 was dancing on my tail. I wasn't being a slacker as I was cruising at around 90..., and then he passed me like I was standing still. Modified blacked out Mazda Speed3..., and when he went to shift guess what.., blow off valve..., Yup, turbo. I let this guy do what he wanted.

On the topic of air leaks.., I found small leaks at the plenum oil drain hose. If it's an old hose replace it and put clamps at both ends. I also had a small leak at the purge valve for the smog system. It's a small round metal valve on the passenger fender wall with a hose attached at the top and bottom. I've found that the hose can leak when old.., but the joint where the hose nipple attaches to the valve leaks as well. I deleted mine and simply plugged the hose, or you can put a little JB weld around the seam to seal things up. Also check the vacuum lines from the fuel pressure regulator valve to the throttle body, and from the throttle body to the interior temp sensor. The rubber hose off the throttle body turns into a hardline and runs along the fire wall on the drivers side. Look for a thin yellow/brownish plastic hardline, mine cracked and was leaking, and as it enters the cab through the fire wall it tuns back into a rubber line. Take the interior bonnet off from under the sterring wheel and check to make sure that rubber line is in good shape and is connected to the back of the interior temp sensor. Mine had fallen off because the end of the hose was stretched out. Just had to cut the bad end off and push it back onto the sensor. Lastly, check the intake boots, all six of them. And the rubber accordian thingy that goes from the AFM to the plenum.

And if you haven't had the plenum off yet.., you do it by taking the 12 castle nuts off the air horns and separate the plenum and horns as one unit from the throttle bodies, and not by taking the plenum off the rubber intake boots. All first timers tend to learn the hard way. Hopefully this will save you some time.

Again, welcome !

[bobby in Derby City]

... for records that the timing chain and tensioners have been replaced. If not, STOP DRIVING THE CAR, and replace the timing chain and tensioners......do this yesterday.

Yes, sir ... I've not work on an S38 nor owned one til Jan. 23 of this year. That's exactly what I did since I've have not talk to (previous) owner yet. Drove her 150 feet from flat bed to garage to four jackstands. Been sitting there ever since ... could only be driven forward in 2nd gear any way since the slave cylinder needs to be bleed

Remember, its a chain.

Don't drive the car until it is replaced. I would not even start it. Others have destroyed their engines with half the miles you have on yours.

Guily of starting her up though Sounds so different than the M20 or M30

On the topic of air leaks.., I found small leaks at the plenum oil drain hose. If it's an old hose replace it and put clamps at both ends. I also had a small leak at the purge valve for the smog system. It's a small round metal valve on the passenger fender wall with a hose attached at the top and bottom. I've found that the hose can leak when old.., but the joint where the hose nipple attaches to the valve leaks as well. I deleted mine and simply plugged the hose, or you can put a little JB weld around the seam to seal things up. Also check the vacuum lines from the fuel pressure regulator valve to the throttle body, and from the throttle body to the interior temp sensor. The rubber hose off the throttle body turns into a hardline and runs along the fire wall on the drivers side. Look for a thin yellow/brownish plastic hardline, mine cracked and was leaking, and as it enters the cab through the fire wall it tuns back into a rubber line. Take the interior bonnet off from under the sterring wheel and check to make sure that rubber line is in good shape and is connected to the back of the interior temp sensor. Mine had fallen off because the end of the hose was stretched out. Just had to cut the bad end off and push it back onto the sensor. Lastly, check the intake boots, all six of them. And the rubber accordian thingy that goes from the AFM to the plenum.

And if you haven't had the plenum off yet.., you do it by taking the 12 castle nuts off the air horns and separate the plenum and horns as one unit from the throttle bodies, and not by taking the plenum off the rubber intake boots. All first timers tend to learn the hard way. Hopefully this will save you some time.

Awesome info garnered(sp?) through time and patience. Thank you so much. Time will be saved. This will help me tremedously when I decide to tackle her. Might be a nice sticky thread

[eddie]

I have had 3 e28 M5s. 165K, 292K and 145K.

All of them needed spark plugs right away. The S38 engine is sensitive to good ignition parts ... especially the spark plugs. They may look OK but they should look nearly new.

If records do not indicate recent replacements - cap, rotor and plug wires should be replaced also.

I feel that too many new owners start prematurely looking into the fuel system. Replace the ignition components first. Then make sure that the fuel tank has been drained/refilled and the fuel filter has been replaced.

Still running sketchy? Broken solder joints in the ECU are common along with corroded electrical connections.

One of my M5s had a nice crack in the rubber intake tube to the AFM. Same symtoms as yours. New tube and the idle smoothed out.

Good luck. My last M5 was running great when it was T-Boned (It was sold to my bodyman who is rebuilding it for his wife).

Good Luck!

Eddie

[texasporschedude]

CHAIN, I got it. The car had new wires, plugs, cap and rotor installed thee years ago, only 5K miles. I plan to pull the plugs this week and have a look. The fuel line, filter, pump was replaced less than 5K miles. Suspension is solid, front end rebuild about 50K miles ago and new springs last year. I need to take care of the timing CHAIN, fix the idle issue and fix the A/C, it is hot as hell this year in Dallas. Should I convert the AC to R134?

[Jeremy]

Should I convert the AC to R134?

I wouldn't in Dallas if R12 is available to you. If you do want R134a, go whole hog and get a new parallel flow condensor, new expansion valve, drain the compressor and replace the oil with the new type, replace the receiver/drier, and replace all o-rings and flexible lines with ones compatible with R134a.

When you look at the cost of a proper conversion, R12 starts to look less expensive.

Jeremy

[Philo]

Suspension is solid, front end rebuild about 50K miles ago and new springs last year.Suspension is solid, front end rebuild about 50K miles ago and new springs last year.

I'd look at front end bushings after all the important stuff is behind you..... CHAIN !

[texasporschedude]

It sounds like the hub nut is a tough one to crack, I am not sure I have the leverage and might to get that off. I read an article that it took a two or three guys and a 4 foot leverage bar and some cutting on the bolt to get it off.

If I were to take this in to replace the timing CHAIN, what would I expect for cost?

[Mark in Toronto]

It sounds like the hub nut is a tough one to crack, I am not sure I have the leverage and might to get that off. I read an article that it took a two or three guys and a 4 foot leverage bar and some cutting on the bolt to get it off.

If I were to take this in to replace the timing CHAIN, what would I expect for cost?

Welcome! As noted in Duke's post, there's lots of info on the timing chain tensioner/guides replacement.

A quick archive search should provide you with an estimate as to how much (parts) and labour required to do the job.

[Randomg]

Last I checked (3-4 years ago), the parts were around 800-900.
I believe the official procedure requires the head to removed, if the head is removed the labor jumps through the roof.

The cars with low miles that have grenaded are probably cars that have sat for long periods of time. These cars have problems that only appear when they are garage queens.

[Cooperman]

It sounds like the hub nut is a tough one to crack, I am not sure I have the leverage and might to get that off. I read an article that it took a two or three guys and a 4 foot leverage bar and some cutting on the bolt to get it off.

If I were to take this in to replace the timing CHAIN, what would I expect for cost?

For the hub nut, rent this tool setup from gkrea1. I have used it twice. Great guy.

http://www.mye28.com/viewtopic.php?t=60008

[texasporschedude]

I spoke to the previous owner today. He had taken it to a BMW dealership sometime ago and asked about timing chain replacement. Apparrently this engine has the duplex chain. the Service Manager told him it should last the life of the car. Did they change the engine in mid year. I know this car was a november build

[mooseheadm5]

I spoke to the previous owner today. He had taken it to a BMW dealership sometime ago and asked about timing chain replacement. Apparrently this engine has the duplex chain. the Service Manager told him it should last the life of the car. Did they change the engine in mid year. I know this car was a november build

They all have a duplex chain (S38s, not the M88 that the euro cars used.) The service manager is correct. The chain will last the life of the car. Unfortunately, the tensioner will go bad and allow chain slap, which will damage the rails, which will allow the chain to skip and then you are fooked. The timing chain job is done mostly to replace worn rails. The tensioner itself can be replaced quickly and cheaply with upgraded parts.

[Karl Grau]

this engine has the duplex chain. the Service Manager told him it should last the life of the car.

It's the plastic guides that are the main concern. The chain is more of a "while you're in there" item.

[texasporschedude]

thanks for the information, I think I will just take it in and get it inspected and go from there. there are plenty of other items on the car that I can work on.

[Philo]

Pictures tell the story...

http://phil.files.infostreet.com/M5_Ima ... CT0017.JPG
http://phil.files.infostreet.com/M5_Ima ... 300072.JPG
http://phil.files.infostreet.com/M5_Ima ... 300070.JPG

The long guide is suppose to be white.., mine was brown and very brittle. If it fails it will probably take out your engine.

Here's the folder for all my chain/guide replacement pics.
http://phil.files.infostreet.com/M5_Ima ... ver_Guides

[Duke]

thanks for the information, I think I will just take it in and get it inspected and go from there. there are plenty of other items on the car that I can work on.

Be very careful here. Inspected by whom? Most BMW "technicians" do not have a clue about a 80's car or the S38 engine.

HEED OUR ADVICE and spend the money now. You can wish it away with a good prognosis form a "technician" that is clueless.

Then you grenade the engine and you will be too embarrassed to show you face here again.

You want to play with a 200K+ S38, your gonna have to pay.

[texasporschedude]

Easy Duke - If I was taking it to someone who knew nothing about these cars, then I should just do it myself. I have a BMW mechanic who has expertise in 80's vintage BMW's - He has a reputable shop and has come highly regarded. This job is more than I want to deal with so I will find the right person to do it.

I appreciate all the information, advise and guidance.

[Duke]

I have a BMW mechanic who has expertise in 80's vintage BMW's - He has a reputable shop and has come highly regarded.

OK, cool. You have found the right people then.

[Randomg]

I've talked to a master mechanic who has owned an e28 m5 at one point, when I told him about all I had read about the timing chain failures on the internet he told me it was rare and that he didn't think it was needed, but if I really wanted him to he would replace it for me. And just to put a name to the opinion (since I'm just some guy on the internet too) it was Jaime at Eastside Bavarian in the Seattle area.

Mine is at 180k and I haven't had any problems. I think letting the engine settle 30 seconds before driving is best.

I think that if you can afford to do the timing chain then go for it, but after reading through many forums over the last few years documenting the failures as well as the replacements of the original components at 250k+ miles, I think that the people that push you into replacing are fear mongering a bit. I think the arguments for doing the work come down to: do you want to risk blowing up an engine on a car where the rebuild is worth more than the car, even if that risk is really low? I can't remember how many failures I've seen documented on the net, and correct me if I'm wrong, but it's less than 6. Anyway, it sounds like you can afford it, so you should definitely do it.

[bojangles]

I spoke to the previous owner today. He had taken it to a BMW dealership sometime ago and asked about timing chain replacement. Apparrently this engine has the duplex chain. the Service Manager told him it should last the life of the car. Did they change the engine in mid year. I know this car was a november build

he could not be more correct. WHen the chain fails (read : If the guide breaks and jambs the chain) the S38 will be FUBAR and the life of the car will be over. From the dealer's standpoint, a replacement engine is worth much more than the entire car. So it will be DEAD.