Motor melt - Break-in suggestions (was rebuild suggestions)

Well, what an adventure - subject: Do a shakedown at a hill climb

Friday forecasted schedule:
-- load the car
-- pack the truck
-- drive to hill
-- recce
-- sleep

Friday actual schedule:
-- quick test drive because I'm paranoid
-- Turbo blows up during said test drive
-- determine retainer nut backed off and destroyed impellers
-- source a new to me turbo (k24 Audi) - have one on the shelf I didn't trust
-- install new turbo
-- start car, hear marble in a tin can noise
-- determine the nut that had backed out of first turbo was hiding in intake hose
-- damaged impellers - but seems to boost ok
-- load the car
-- pack the truck (including spare turbo I didn't trust)
-- drive to hill (arrive 1am)
-- no recce, sleep

Saturday forecast schedule:
-- setup service area
-- tech/register
-- Fam run write notes
-- several runs adjust notes and work w/new co-driver
-- eat a meal, drink a beer, sleep

Saturday actual schedule:
-- setup service area
-- tech/register
-- 3/4 of the way up the FAM run, turbo looses boost, guess them impelers aint making it.
-- car overheats, ride it down, no power, all brakes (they work
-- Starts to rain like mad!
-- Remove turbo, discover cold side is different and hot side is indexed different
-- Rebuild 1 turbo out of 2
-- Install, start, all seems good except temp is immediately high - figure it needs to burp.
-- boost is good, but overboosting.
-- run up and down the hill a few times in civilian car to write notes and work on pace

Sunday forecasted schedule:
-- remove manual boost controller from equation and run on spring only
-- ensure temp is stable
-- do Fam run adjust notes
-- run the rest of the day

Sunday actual schedule:
-- run spring only, set to boost to 18lbs
-- temp ok, a little high but stable
-- 1/2 way up Fam run, overheat, pull over, thought I'd heard a motor knock through the Peltor
-- coast down hill w/power
-- sure enough motor know
-- pack up - go home

Analysis:
-- pull pan, full of bearing material
-- pull big end bearings, copper colored !
-- pull mains, bearing material started to damage mains
-- cams show small flecks of bearing material
-- found a glob of solder attached to the thermostat (over zealous brazing of the radiator. Solder particles must have made their way to the t-stat and collected, then stuck to it, preventing it from operating properly - weird). I plan on running w/o a t-stat, at least in the warm months.

A local guy had a brand new factory bottom end (yes 20yrs old and still in the cellophane). So plan on putting that in, w/my head (with all of 15miles on it).

I've brought the head to a machine shop to be tanked - plan on replacing the hydraulic lifters with used ones that are in good shape but have not been in a bearing contaminated motor.

Is there anything else I should watch out for putting this puppy back together?

Thanks,

Vittorio -



Edited 1 time(s). Last edit at 06/10/2011 04:08PM by vbares.

Never use used lifters with any cam, used or new, only with the cam they were broken in with. And only on the exact same lobes. The lifters and cam lobes wear in together under very high contact pressures and changing usually damages/destroys one or more cam lobes. Only use new lifters.

I've run a cam with a few flakes of bearing stuff on them, with no dire consequences, but that's not a guarantee.

Make sure you use a good cam lube with MoS2 in it anytime you rebuild an engine.

Aluminum head? Getting it COLD tanked NOT hot tanked, right? The shop should know better but mistakes have been made by junior shop workers.......Are you having it checked for cracks and/or warpage? The overheating could have started with a minor head failure.

18 lbs boost is pretty serious; especially under the almost constant, heavy load of a hill climb. Had you run the engine under those conditions before? Was the engine knocking due to bearings, or detonation? (Hard to tell with a helmet on...) Was the orignal bottom end old? Sounds like you might have had some marginal oiling problems that started up with, or contributed to, all of this. Otherwise, the boost was just too much for the bearings to take it, IMO. How do the rings and pistons look? I would look at those for signs of excess heat/boost/detonation?

The 'new' block: Seals and gaskets will like be old, and likely hard and/or shrunken. So expect some leaks from the main seals (front and rear) and maybe the pan gasket. Make sure you prime the oil pump! If it cannot be primed externally, I would take it out (and check impeller clearances while it is out) and pack it with Vaseline. It does not make sense to me to start with any used engine and not take at least the oil pan off and inspect some things.

I would run with a low temp thermostat rather than none. Any worries that there is a lot of solder in the radiator? You could have blocked tubes. I would back flush it, and tap it a bunch and shake it around, gentle whack it on the ground, etc., to try to knock any junk loose.

Mark B.

A 10% blockage in most radiators will put them on the edge of losing efficiency. Solder bits can easily block radiator tubes. Thermostats...don't take it completely out as that can overheat the car. The water needs a cetain amount of contact with the radiator tubes to echange heat. Not having a tstat can cause the water to flow too quickly to exchange heat. Some restriction is needed, if you don't want to run a tstat then you may find that gutting the tstat to be effective. Just remove the center portion and use the outer part.

Yeah my machine guy was smarter than me I said 'hot tank' he 'cold tanked'...

18psi is not very much for these motors - my daily, w/the same motor runs 28psi of boost all day long w/no issues (RS2 package).

Yes, the bottom end was unknown, used from the wrecker. Not pinging, all cylinders looked good, no evidence of detonation.

I've changed the seals - oil pan gets a windage tray, so also new gaskets. Head gets new cam seals. I'll take a look at the oil pump as well, good call.

As far as using used motors - ya live and learn

I like the idea of gutting the T-Stat and running w/that. Also will give the rad a tap or two and flush.

anything else?

OK on the pistons; good that you checked that. I will bow to your expereince with the boost level on these motors. But I'll bet you are not at 28 psi for minutes on end in the daily driver.....but you could be that crazy!

BTW, I never put our Mitsu 2.6L motors together anymore without a spanking new oil pump; too much to loose in the turbo department with just a moment's drop in oil pressure.

Do you have real oil pressure and boost pressure gages? I long ago stopped believing the ECM 'manufactured' boost numbers. Those gages are very essential and cheap diagnostic tools IMO with any serious boost level.

Good move on the new seals and gaskets.

Is this a timing chain engine or belt?

I read Gen's info on radiators....that's one thing they truly don't build like they used to. My son just replaced the one in his Dakota P/U; only 8 years old.

Best of luck,
Mark B.

~18 psi is what they ran from the factory (well close enough)

I'd toss a set of 7A cams in there if you haven't yet (they are worth a couple hundred RPM less lag and a suprising amount more power). Remember that there is a tolerance for the cracks in the head (these heads are always cracked)

I'd keep the thermostat, these motors like their heat. On the freeway, I cant keep the car as warm as I would like it, so on a long straight stage it may prove benneficial.

maybe shoot some of the 20v guys on the 'geek a message

It is a Timing belt motor

Also keep in mind the rods are going to be your limiter in the power dept. 450 lbft of torque is all they will take in a daily driver, Could be a good time to upgrade.



Edited 1 time(s). Last edit at 06/02/2011 04:40PM by aj_johnson.

Also, I have a "spare" turbo K24 or K26 if you need to borrow them let me know.

On the 7A cams - they do increase power up high, but they also increase lag. My son put those into his drifty car...I'll leave well enough alone on that.

The rally car won't do 450lbs of torque with the turbo it has - and with a 36mm restrictor - I don't know if it ever would. (the daily on the other hand...)

Mark - true enough, not at that boost level for minutes at a time. But that's the daily.

On the gauges, VDO gauges for oil pressure and boost. Also have EGT and those temps are generally good.

any other thoughts on the t-stat? So far have 2.5 approaches - would love to see a consensus.

AJ - would love to have a K24 as a spare...

hmm. I dont remember having increased lag... but it was a couple of years ago. sent you a pm

I think it's always best to run with the tstat but it's better to run with a gutted one than none. IF the tstat isn't sticking then they only control the minimum temp a motor runs. Radiator capacity and efficiency control the maximum temp.

And in case anybody is curious there's serious relationship to water temp, block (bore) wear and power produced and fuel consumption.
cliff notes: the hotter the better for everything, and conversely with water temps around 140-150, fuel consumption is high, poop output low and bore wear drastic.

cf Continetal publications way back in the 30s

So temp UP and watch for localised overheating in the head leading to detonation.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Good info - leaning towards putting the t-stat back in.

In Italy they have a saying that loosely translates to: Once scalded with hot water, you then become scared of cold water - how apropos...

there were clearly mitigating circumstances to the t-stat failure - no need to be paranoid about t-stats I suppose - makes sense that the motor wants heat, the sytem wants some pressure/restriction. I've significantly improved cooling with a shroud and have moved everything out of the way from in front of the rad, so cooling should be much better....

Thanks!

I always turn to you guys for a diversified view...seems to work

Just to clarify, the thermostat's only role in creating pressure in the cooling system is to regulate the minimum coolant temperature. The thermal expansion of the coolant causes a rise in pressure. The system pressure is regulated by the relief valve setting of the radiator cap.

I agree with John, a hot engine is a happy engine. I have recently had to deal with the appalling wear caused by low coolant temperatures. Diesel engines don't like to be left idling at -50F.

---

Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

http://www.motorgeek.com/viewtopic.php?f=10&t=37621&hilit=7a+cams

Dyno results of the different cams on the same motor. Looks like the stockers are a bit better under 3200 rpm... do you really spend that much time down there? I don't remember any increased lag, and looking at the sheets, I cant see anything more than 100rpm at worst.

I would reccomend the cams, if you dont like them put them in the daily driver. You will definitely like them there. 7a cams can be had for as cheap as 150 bux. That is cheap for an extra 15-20 lb fts

Quote
aj_johnson
http://www.motorgeek.com/viewtopic.php?f=10&t=37621&hilit=7a+cams

Dyno results of the different cams on the same motor. Looks like the stockers are a bit better under 3200 rpm... do you really spend that much time down there? I don't remember any increased lag, and looking at the sheets, I cant see anything more than 100rpm at worst.

I would reccomend the cams, if you dont like them put them in the daily driver. You will definitely like them there. 7a cams can be had for as cheap as 150 bux. That is cheap for an extra 15-20 lb fts

Seems typical intrawebz forumz insignificant differences touted as BIG!
We wanna see
25% or more MOAR! if I's gonna get excited.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.