Ranger's Dec09 motor rebuild thread (lol)

#1

(not so)Quick review.

Dec08 Molitor hoses up my perfectly serviceable motor.

Feb09 After freezing my ass off for 4 days staking out Molitor’s shop, the Police help me get my car back.

Feb09 The fabulous gents of SpecE30-SE, in an epic adventure, help me (they did most the work) replace the motor that Molitor hosed up with a junkyard motor at the track. It took us 4hrs.

Feb09 My junkyard motor turns out to be a weak POS.

Mar09 My junkyard motor can’t hold oil pressure.

Mar09 I start rebuilding the Molitor motor and I buy a brand new head. But when the head arrives it does poorly on compression and leakdown tests. I spend weeks installing and testing my 3 heads, because I assume that I’m messing up the compression and leakdown tests. After a dozen iterations, I became the fastest E30 head installer in the world today.

Mar09 I gouge the deck of my new head so I have to take it to a machine shop and get it decked.

Apr09 After arriving at some comfort level that my compression and leakdown tests can be trusted, I try a drip test on my heads. After many long conversations with the folks that built the head I send it back to them over their objections. They call back later and say the the head was indeed messed up.

Apr09 I get the head back and have a local shop help me with the build of the bottom end. They build it with a little assistance from me, and conclude that a main bearing has too much clearance and the crank has to be machined to fit an over-size bearing. After talking to the machine shop at length, I build the bottom end myself and the clearances turn out fine.

May09 I fail to install a head locating pin that goes on the block’s deck and the head doesn’t get positioned just right. The result is a slight pinging noise. Having seen 3 “pro’s” put on heads without the pin I just didn’t think that it was a big deal. Having installed the motor into the car myself, I take the car to the shop to figure out the pinging noise. They charge me >$1k to figure out that the pin is missing and a piston head was just ever so slightly whacking the head and making the “ping”.

When the local shop removed my head the rocker arm shaft retaining pin popped out and no one noticed. I put the head on the motor and go to RA and race with my fabulous engine and the head fails because the rocker arm shafts rotated. My $2k head is ruined.

May09 The shop that built my head are great Americans and they build me another head at cost. I install it and drive on. Later dyno results are a little disappointing for a new head on an 0.020 motor, but I’m beyond caring.

Dec09. The coolant hose on the block near the starter failed. Coolant temp gauge didn’t really give much warning because once you lose some coolant, the sensor is no longer touching coolant flow. There’s something for us all to think about there. It was the oil temp gauge that told Simon that there was a problem.

When I had the motor out last Spring I had considered tapping the block and putting in a bolt to delete the hose entirely, but I had instead just cut it at 5" and blocked it off with a bolt and hose clamp. The hose failed at the block.

That’s as much history as I have the patience to type.

#2

Chapter 1.

Even tho the motor sounds like a bad rod bearing, I decided to look at the head first. I think that the head is more likely to fail due to overheating then a bearing.

Pulled the rocker arm cover off. Head looks fine.

Compression test is kinda low everywhere, but #5 might have an issue. 0 psi is bad, right? .

#3

Something does not add up.

“Coolant temp gauge didn’t really give much warning because once you lose some coolant, the sensor is no longer touching coolant flow” This may be true but as the coolant is leaking out, the sensor is in a mixture of water, steam, and superheated air = pegged gauge. I am aware that you are a guage maniac but was the factory guage still hooked up? Was this was one still “straight up” as the oil was getting hot? Maybe your aftermarket water temp guage failed?

Secondly - I can understand how superheated oil could equal a earing failure. But if I read Simon’s post correctly, the oil was creeping up to 280F. While that is hot, it is not too damn hot as even Kmart oil can withstand 300F for a short while. Plus, why would an engine sound fine on an in lap (even if it was over heating) and then clatter when water was added. It makes no sense that adding cool water to a hot engine would cause an instantaneous bearing failure. Something else broke.

What do the engine experts say?

Don

#4

I don’t believe Water Wetter raises the boiling point of water by any appreciable amount. I the absence of pressure, the water boils at 212ish. Steam is not hotter than that unless pressurized. So the gauges show normal temps.

I put in a low pressure idiot light (if the foo shits) that comes on below 5 or 6 psi. I saw another guy nuke a motor by losing coolant so it seemed like a good investment.

I wonder if the cold water warped something enough to eliminate a tight clearance that had previously existed, stressing a rod or something to the breaking point?

#5

Me thinks turning the motor off when it was hot was the kiss of death. Engine temperature rises when the motor is turned off and water circulation stops. Restarting the motor after the block continued to expand probably spun a bearing. My guess anyway.

#6

Gasman wrote:

It’s not that simple. Engines quit generating heat when they are turned off. Sure, the transfer of heat also stops. So you’re certainly right that the flow of coolant stopping allows localized high temps. But if a motor is overheating you can’t just stand there and let it continue to generate heat.

The high heat points are the combustion chambers. The coolest place in the whole motor might have been the rod and main bearings because not only is the crank a long ways from the combustion chambers, but the crank is also getting all sorts of cooled oil. My oil cooler is 3.5X the size of OEM.

#7

Steve D wrote:

Tell me more about this pressure sensor.

Don. I’ve an aftermarket VDO temp gauge. The sensor is in the OEM location in the thermostat cluster. I don’t trust OEM gauges very much because a lot of them are “weighted” such that it takes a lot to get them out of the “ok” range.

#8

Looking for a low water level sensor?
Oops,don’t delete the BMW overhead unit…

RP

Ps,immediate coolant loss
show on the gauge.

#9

the oem water temp guage isn’t buffered in the e30 btw. i’m just waiting to see how many extra guages ranger will add to guard against this next time around. will wp be the new op? :wink:

#10

Patton wrote:

[quote]Looking for a low water level sensor?
Oops,don’t delete the BMW overhead unit…

RP

Ps,immediate coolant loss
show on the gauge.[/quote]

Robert, what does that mean?

#11

Well shit. It didn’t take long for my first screw up.

In order to get the head off in a hurry I pulled the spare motor off of the hoist and used it to lift the head and manifolds.

The pistons and cylinder walls look ok, that’s good news. So I wrestled the head and manifolds over to see where I’d melted a hole (remember 0 psi in #5) and to my surprise the head looked fine.

And then it dawned on me. I did the compression test in a hurry because it’s a 2 person job and I only had a buddy assisting for 15min. And I flat ass forgot to put each cylinder at TDC for it’s test. So of course #5 showed no compression, it had a g’damned valve open. God I’m an asshole.

So I might have pulled the top end off for nothing. Grumble grumble.

But since the head, pistons and cylinder walls all look ok, next I’ll have to get the car good and high, lift the engine up, pull the pan, and look at the bearings.

Here’s a thought for everyone. I’ve had to install and remove downtube nuts a dozen times this year. And they are always a little loose. This last time I had tightened them as tight as I dared, and tonight I found them to be not very tight at all. A couple times a year I’d check your downtube nuts.

#12

what’s the condition of the head gasket?

can you turn the motor by hand?

#13

Motor turns by hand easily. HG looks fine, but my perception is that sometimes blown HG’s aren’t visually obvious. Besides, it’s the clanking sound that I’m chasing down, and no matter what condition the HG is in, it didn’t clank.

I’m going to order a Goetz HG. There was a good thread months ago on E30tech re. HG’s. Nobody seemed to like the Victor Reinz HG’s that I’ve been buying.

#14

yeah i recall that. never been able to source those easily however. i guess your going to have to check the bottom end, at least the head is ok, get it checked out however.

#15

kishg wrote:

Pelican sells the Goetz HG.

I had the same hose spring a pin hole leak on me at CMP, lucky for me I came in because my tires were shit before it did any real damage, temp guage never moved. If it weren’t for the steam coming out from under the hood I would not have found it and raced the next race which would probably have resulted in a major failure. Lucky for me Bob Shields was right there when I came in, I like being lucky!!!

Greg

#16

I talked to Bob at RA the day after the overheat. As soon as I mentioned overheating, he said “wait, don’t tell me, the hose on the block by the starter”. He also mentioned that it had struck you.

Removing that hose and sticking a bolt into the block needs to be part of basic SpecE30 prep.

#17

Heater Replacement Plug Set
For the BMW e30 (M20 Motor)
To eliminate the use of heating system
Recommended for race use only

See AKG’s website under E30 Engine / Drivetrain

http://www.akgmotorsport.com/catalog/view.php?image=http://www.akgmotorsport.com/catalog/images/PL30M20lg.jpg

#18

Ranger wrote:

IIRC, we used part #1009 from Pegasus (http://www.pegasusautoracing.com/productdetails.asp?RecID=8). The switch comes on at 4 psi so the light will be on when the engine is cold, but works when on track.

Personally, I like having heat/defrost for cold and/or rainy days. Some would argue there is increased risk of the heater core spraying scalding liquid if it fails, but seeing out the windshield has always been a big priority of mine.

#19

Ranger wrote:

[quote]Patton wrote:

[quote]Looking for a low water level sensor?
Oops,don’t delete the BMW overhead unit…

RP

Ps,immediate coolant loss
show on the gauge.[/quote]

Robert, what does that mean?[/quote]

Another typing oops.
PS, immediate coolant loss WILL NOT show on the gauge.

#20

Who wants to chip in with me and get Patton a “Mavis Beacon Typing for Old Timers” computer program?

If he could only tell us half of what he knew…

(**remember all due respect)