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Engine rebuild/replace interval


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Hello all,

 

 

 

My team and I have been pondering this for a bit, and none of us have come up with a decent answer, so I toss the question to the masses:

 

Backstory: our eighth-hand ford contour engine has an estimated 175 hours under racing conditions.  No clue how many miles were on it before it went in the car.  We've got a spare engine we know has 130k miles on it ready to go in the car, but can't really decided if we want to hit Sebring with an untested motor.

 

So then, how often (in hours or races or miles) do you replace/rebuild your engines?  Is this a 'when it scatters metal all over the track' kinda thing, or does anyone go with 'it's been in there for x amount of time, let's replace/rebuild'?

 

Cheers!

 

Edit: It's a 98 Ford Contour; 2.5L duratech V6

Edited by krispykritter
k and thousand are the same thing
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Teardown/inspect/replace whats broke/reseal every ~100 hours, but we're on the aggressive end.  Usually lash valves every ~30, and lap or grind valves on the 100 hour rebuild.

 

I like to take the engine out every 50 hours to do an in-depth leak check, look for cracks in the exhaust, and put a wrench on everything I cant get to while it's in the car.  Find a surprising amount of stuff that way, especially in the areas that get hot.  

 

Things found on the last 100 hour rebuild (engine seemed to run fine):

Cracked exhaust

slightly bent valve

worn guides

cracked oil control ring

moderate main bearing wiping

head gasket water leak (no compression loss, just a dribble out the side of the engine between head and block)

 

Again, I'm a bit on the aggressive side for rebuilds, but you can find a lot.  I always disassemble, inspect, and reseal an unknown motor, even if I end up not replacing anything internal.  Lets you know exactly what you have.

 

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Well, for the last four years I ran a rotary...  so you don't care what I have to say...  but, we had one engine last 130 hours before it chewed a water seal...  oh, and still ran 14 hours with it pushing water out the tailpipe.  Our second engine is currently sitting at 24 hours....   all were rebuilt since rotaries are usually dead when you find them anyway...

 

 

Edited by Justin9
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I did a leak down test and hit 40% on a couple of cylinders but it was only using minimal oil.  So we went and did another 28 hours at Laguna as it was the last race before the 2017 rules change after which we were swapping engines anyway.  Third place on day two, did not run well on days three and four.  

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Thanks for the input, guys. 

12 hours ago, Justin9 said:

we had one engine last 130 hours before it chewed a water seal...  oh, and still ran 14 hours with it pushing water out the tailpipe.

Yeah - rotaries are their own animal, that's for sure!  But still, seeing you get 130 hours out of a rotary makes me think we can probably get roughly double that out of a standard piston engine.  Mebbe.

 

12 hours ago, Hi_Im_Will said:

Teardown/inspect/replace whats broke/reseal every ~100 hours, but we're on the aggressive end.  Usually lash valves every ~30, and lap or grind valves on the 100 hour rebuild.

 

I like to take the engine out every 50 hours to do an in-depth leak check, look for cracks in the exhaust, and put a wrench on everything I cant get to while it's in the car.  Find a surprising amount of stuff that way, especially in the areas that get hot. 

I really really wish we could do that, but the contour is quite a beast to get the motor out of - A miata or 240sx I can get the engine and trans out in under three hours by myself, but I'm dreading pulling the engine out of this thing!

 

We do go over things fairly well between races, go through all fluids and check everything we can reach, but definitely haven't done anything like your 100 hour maintenance.

 

General consensus so far seems to be that the current motor is rather long-in-tooth for an engine used for racing, huh?

Edited by krispykritter
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We recently started doing leak down tests and compression checks and keep records. Both easy enough to do between races and it gives you some idea of your motor's health.

Look at the spark plugs while they are out and get a good read on each cylinder.

Might want to consider oil analysis as well. We use Blackstone Labs.

 

Of course none of these "procedures" in and of themselves are predictive, all together they give you a pretty good idea of how your motor is running over time.

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We used to track compression and spark plug colors, and the occasional oil analysis. But after a few seasons, we saw a pattern. The engines lasted 5-6 weekends before losing compression and blowing the head gasket. We kept engine temps below 210, and used ARP studs. But the stock engine just wasn't up to the challenge. So we started keeping a rebuilt one at the ready, and swapped once we saw signs of head gasket failure. Then get that one rebuilt and ready to go. We can have it running with the new engine in less than 3 hours after pulling it into the garage. 

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13 hours ago, Hi_Im_Will said:

Teardown/inspect/replace whats broke/reseal every ~100 hours, but we're on the aggressive end.  Usually lash valves every ~30, and lap or grind valves on the 100 hour rebuild.

 

I like to take the engine out every 50 hours to do an in-depth leak check, look for cracks in the exhaust, and put a wrench on everything I cant get to while it's in the car.  Find a surprising amount of stuff that way, especially in the areas that get hot.  

 

Things found on the last 100 hour rebuild (engine seemed to run fine):

Cracked exhaust

slightly bent valve

worn guides

cracked oil control ring

moderate main bearing wiping

head gasket water leak (no compression loss, just a dribble out the side of the engine between head and block)

 

Again, I'm a bit on the aggressive side for rebuilds, but you can find a lot.  I always disassemble, inspect, and reseal an unknown motor, even if I end up not replacing anything internal.  Lets you know exactly what you have.

 

 

I would listen to Will when it comes to engines.  I have not seen Will out of a race because of engine problems since Road America when they started with the e30.  I just don't have the time or the extensive knowledge as he does. 

 

56 minutes ago, wvumtnbkr said:

Wow!  Some people take this stuff seriously!

 

I hope to get about 4 years of racing out of any engine between teardowns...

 

That was my mindset when I was throwing in junkyard motors too.

 

26 minutes ago, Doc said:

We recently started doing leak down tests and compression checks and keep records. Both easy enough to do between races and it gives you some idea of your motor's health.

Look at the spark plugs while they are out and get a good read on each cylinder.

Might want to consider oil analysis as well. We use Blackstone Labs.

 

Of course none of these "procedures" in and of themselves are predictive, all together they give you a pretty good idea of how your motor is running over time.

 

This is pretty much what I do.  I do a compression test pre and post race.  I look at plugs now and change them as needed.  Oil analysis is always great on not only your engine oil, but transmission and diff oil.  I would consider cutting your oil filter as well. 

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1 minute ago, Crank Yankers Racing said:

 

This is pretty much what I do.  I do a compression test pre and post race.  I look at plugs now and change them as needed.  Oil analysis is always great on not only your engine oil, but transmission and diff oil.  I would consider cutting your oil filter as well. 

So...what are you looking for in trans and diff oil analysis? I would think that most of the components are similar materials...

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2 hours ago, krispykritter said:

I really really wish we could do that, but the contour is quite a beast to get the motor out of - A miata or 240sx I can get the engine and trans out in under three hours by myself, but I'm dreading pulling the engine out of this thing!

 

We do go over things fairly well between races, go through all fluids and check everything we can reach, but definitely haven't done anything like your 100 hour maintenance.

 

General consensus so far seems to be that the current motor is rather long-in-tooth for an engine used for racing, huh?

 

With my new lift and the Camaro crossmember, the GM engine out the bottom process is going to be a pretty straightforward process....  I can remove a few connections, raise the body, and do the engine work with the front end all together, put the body back down and put it back in fast....

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36 minutes ago, TBone said:

We used to track compression and spark plug colors, and the occasional oil analysis. But after a few seasons, we saw a pattern. The engines lasted 5-6 weekends before losing compression and blowing the head gasket. We kept engine temps below 210, and used ARP studs. But the stock engine just wasn't up to the challenge. So we started keeping a rebuilt one at the ready, and swapped once we saw signs of head gasket failure. Then get that one rebuilt and ready to go. We can have it running with the new engine in less than 3 hours after pulling it into the garage. 

I'm starting to have a lot of respect for this ford engine - pretty sure it's got something like 14 race weekends on it, it's all stock parts, and still was running just fine at the end of Daytona.  Not the fastest thing but seems to be well-built.  The transmission is definitely proving to be more fragile than the engine.

 

8 minutes ago, Justin9 said:

 

With my new lift and the Camaro crossmember, the GM engine out the bottom process is going to be a pretty straightforward process....  I can remove a few connections, raise the body, and do the engine work with the front end all together, put the body back down and put it back in fast....

If we had a lift, that would be our plan, but none of us do.  Supposedly taking it out the top isn't terrible, but we'll see soon.

 

Definitely seems like it's a  good time to yank the motor, get the 'new' one in there, and start the rebuild process with the old one.

 

Thanks for the input guys, it really helps.

 

 

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1 hour ago, Doc said:

So...what are you looking for in trans and diff oil analysis? I would think that most of the components are similar materials...

 

Something that shows your that your diff or transmission is putting metal flakes in the oil or that stands out of the ordinary.  It's a good analysis to do so you can catch something and replace it before it fails at the track.

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9 minutes ago, thewheelerZ said:

Is that kind of like an Italian shower?

 

No, the engine is not lathered up with cologne.  

 

We run so much timing advance that the only way to keep the engine from detonating is to run AFRs down in the 10s. On extended yellows the plugs will foul and we then have to run a straightaway or two on the rev-limiter to 'clear it out'. Hence, the Italian tune up. 

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1 hour ago, Ronh911 said:

Tear down, inspection and new rings every 100hrs. New rod bearings at 50-70 hrs.

 

What a difference.  I'm still on the rings and rod bearings BMW stuffed in the engine 30 years ago, but on the second set of valves, 3rd set of guides, 5th set of main bearings, and about to replace the cam for a second time.  

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6 hours ago, Crank Yankers Racing said:

 

No way I would use a magnet in my oil.....that's just madness!

What ya do is get a couple of those flashlights with magnetic bases, take the magnets off and put them in when you do an oil change.  Then you just check and see whats stuck to them when you do the next oil change, they drain right out with the old oil.  Its really simple, all the cool kids are doing it.   

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