Track Day at High Plains Raceway (Good News, Bad News and O Sh!t News)

[scannon]

The good news is I had a great afternoon at a half day Test and Tune session. First time out in the Caterham this year.

Bad News #1: I was experimenting with tire pressures to see if what people keep telling me about running low tire pressures in Sevens is true. I started with 19 F and 21 R which quickly warmed up to 23 & 25 psi. It felt good so I started lowering the pressures looking for 16 F & 18 R. Handling started to degrade each time I lowered the pressure but I persevered and at 19 F & 21 R I spun on turn 8, a blind, off camber and slowest corner on the track. I not only spun but the dirt off the track was still muddy from a heavy rain the previous night. It was so muddy I couldn't get the car moving. I had to rock back and forth, sliding sideways all the time to finally get back on track. When I got back to the pits the fenders were filled with mud as well as splatters all over the body.

I was in my pit stall getting the large clumps off when the track manager came along with the water wagon and said to follow him and he would clean it off. We went to a remote area of the pits that had obviously been used for mud removal before and got the worst of it off.

Bad News #2: I decided to go back to the 23 & 25 pressures and did a couple of laps. It felt fine so I took on a passenger who had been waiting for a ride. Off we went and made it as far as turn 8 again. This time I confused it with another blind turn, set up all wrong and went in way too hot. Off we go, backwards this time but clear through the mud. However, far more mud ended up on the car including inside as the pictures show. Back to the pits, the manager said, you know how to start the motor on the water wagon, do it yourself this time. I was ready to quit for the day but he suggested I take a breather once the mud was off the car and get a few more laps to take home a happy memory of the day.

O Sh!t News: With a reasonably clean car and good tire pressures I went out again, being very cautious around turn 8. No problem but on one lap as I shifted from 3rd to 4th I somehow got 2nd and over revved the engine. I backed off, checked oil pressure and temp, both were normal and the engine sounded OK and still felt stong so I ran a few more laps. Somewhere around turn 8 (again!) I suddenly smelled antifreeze, didn't see any on the windshield but when I looked into the passenger compartment I saw liquid dropping from under the dash onto the floor. A second look at the temp gauge showed it had shot up from the normal 100C to a little over 120C. I light footed it back to the pits.

Upon opening the bonnet, I discovered that the cap for the catch tank had blown off and the tank was empty. I found the cap down on top of the transmission just back of the fire wall. I started the engine and added a little water to the tank. The engine seemed to suck it in reasonably fast and the temp gauge started to drop. I added about 2 quarts total but then I started hearing violent boiling sounds and water was coming back into the catch tank. I shut it down.

I let the engine cool while I gathered things up to go home as it was near the end of the day anyway. When I started the car to put it in the trailer I noticed that sickening uneven grind on the starter motor: ruh, ruh, thump, ruh, repeat. The sound of a dead cylinder. I got it in the trailer and home.

This evening I unloaded it into the shop and checked to see if there was water in the oil. No indication. I pulled the plugs, all looked the same and normal light brown in color. I did a compression test: 60, 40, 30, 80 psi. My early, hopeful diagnosis is blown head gasket. My compression gauge has always read low so I am borrowing a Snap-On gauge from a friend tomorrow and checking it again.

[slngsht]

damn skip, that's a rough day. props for sticking with it though

[MightyMike]

Skip,

Sorry to hear about your day at HPR. Please keep us posted. Hope it's nothing serious and that you have your car back together for the Concours on August 8th.

Mike

[Kitcat]

Skip:

What a day! I am worn out/bummed out and it wasn't even me. I guess the upside is there were no injuries to driver or passenger.

Back when I tracked a Miata, I occasionally make the same shifting error, but always backed out of it as soon as I realized something was wrong and managed to avoid the big over-rev.

Good luck w/repairs!

Mike

[Hank]

Skip, glad to see you and your passenger made it out ok. I see a gopro camera on the dash. Can we see the footage of the spin? 

[scannon]

Skip, glad to see you and your passenger made it out ok. I see a gopro camera on the dash. Can we see the footage of the spin? 
That is a go pro camera, first time I have used it. It was on for both spins as well as when the coolant started leaking. I need to RTFM to find out how to download the clips onto my computer. I will post them on YouTube when I get it done.

First priority is to fix the engine. Before I left for the day this AM I took the schrader valve out of the hose for the compression gage and fed air into #1 cylinder at TDC. It was immediately obvious to the most casual observer that air was coming out of #2 & 3 as fast as it was going into #1. Further evidence pointing to a badly blown head gasket. I will start the teardown in Sunday AM.

I did start the OP with saying I had a great day at the track. I'm not bummed at all about the engine. I've destroyed three engines at the track and wrecked the Miata there as well. Problems like this are part of the price of fun when you track a car.

I am perplexed about the suspected blown head gasket. I've put 90k hard turbo charged miles on my Miata with about 7k of those on the track and never had a blown head gasket on any of the four engines. I have used factory head gaskets on all those engines.

No one was hurt and my passenger thought it was a cool ride even if we only made half a lap. He even helped me clean off the mud.

Mighty Mike, I won't be at the concours on the 8th as that is the weekend of the Flyin Miata Summer Camp, much more fun than a car show and includes a track day. This year is the 13th annual and I have been to all of them.

I will be doing the British Motoring Conclave in September.

[MightyMike]

I'll see you at the Conclave Skip! Have a great time at the Flyin' Miata camp.

Mike

[TLRracer]

I love it!

What a great track day experience. I don't know why but I always loved crashing when I was practicing or racing. I never minded blowing stuff up although it didn't happen very often. Like you said all part and parcel of racing. Of course one time I forgot to put water in the NSR - that worked well!

But crashing just shows you that you mosey-ed on up to the edge and peeked over. It is something you have to do to become faster. It always hurt on the bike though, low sides not too bad, but I did get some stitches from the high sides! Crashing a car is really kinda fun compared to the bike - if there is a lot of run off then cleaning off mud isn't such a bad way to fare after a mishap.

[scannon]

Here's the video of the second spin. YouTube - Mud Slinging (http://www.youtube.com/watch?v=os6npwoGCtE)

The vid of the first spin doesn't really show anything and the other video I shot is too long for YouTube and I don't have software to edit it down.

[Kitcat]

Thx, for posting, makes me want to get a GoPro.

Interesting spin:Cold tires? Off line? In too hot? Braking mid turn? Effect of the passenger's additional weight? All of the above?

You were hanging out the rear pretty good a turn or 2 before but this one seemed to catch you by surprise, no counter-steer, the car just whipped around on you. Nice track on which to spin tho, nothing to hit but mud.

I also subscribe to the: "How do you know where the limit is unless you exceed it" theory of racing. I get no thrill out of wrecking my car tho.


Mike

[MightyMike]

Looked like you weren't the first to go off-roading in that corner.

Kitcat - concur

Mike

[Kitcat]

MM-I definitely concur-looks like a very popular place to "plow the field".

[scannon]

Mike,

Tires should have been hot by then, I was only in the pits for a few minutes. As I said in the original post, I confused this turn with another blind and similar looking turn. I came in way too hot and knew before the spin I wasn't going to make it. I just let it go and put both feet in. The extra weight of the passenger probably was a factor as well. I've got to learn to say no to all the requests I get for rides.

The track is only two years old and you would have to try real hard to hit something solid although others have done it there. It's a technical track and I still don't have it all down as evidenced by my confusing it with another turn. Lots of elevation change, blind corners and an off camber turn (the one that got me twice this day).

I just spent the morning cleaning all the mud off the car. There must have been something acidic in the mud as there are some etched areas that I cannot remove with a cleaner wax. Fortunately, all of the exterior blue paint is covered with clearbra except for the area around the louvers in the bonnet. I can always have the affected areas replaced. This afternoon I will pull the head to see what I can find out about the compression problem.

[scannon]

Looked like you weren't the first to go off-roading in that corner.

Kitcat - concur

Mike
It's not the first time I've been off in that corner by a long shot. I think at least one off for every day I've been there. It is a popular place to go agricultural. It's the slowest turn on the course, it's blind and at the top of a hill and a little bit off camber. Great fun but hard to master.

[scannon]

Pulled the head off this afternoon and NOTHING. No indication of a blown head gasket that I can see. There is a shiny ring around each cylinder on both the head and block with no breaks or burn through marks. The valves all "look" like they are closing properly. No cracks or gouges in the cylinder walls or combustion chambers.

I can't come up with an explanation for the low compression, the dead cylinder sound when cranking the engine, the blowing air into #1 at TDC and hearing it come out the spark plug holes on #2 & 3 with an open tube engine stethoscope.

No sign of a slipped tooth on the timing belt and even if it had slipped a tooth or two there is no way more than two cylinders can have open intake valves or exhaust valves at the same time.

Any suggestions?

[bsimon]

Hard to tell from the pictures, but pics 8 and 9 look as though there is a gas path between the cylinders at their narrowest point, under the gasket's sealing ring. I don't quite see the same in pic #7 or 8, but it's hard to tell.

Once the gas is in the soft area, the next port of call would be the teardrop-shaped water jacket holes.

It sure sounds like you're getting some crosstalk between cylinders.

[Hank]

Skip, it looks like the gasket is damaged between the 2 cylinders on the right side of this photo and an indication between the 2 cylinders in the middle of the photo as well.

http://www.usa7s.com/vb/attachment.php?attachmentid=2026&d=1280106774

[bsimon]

Again, the photos make it hard to see the actual flow path, but I think Hank's spotted the same thing I have.
Note that it's on the block side of the gasket, as well.

Can you zoom in to one of those areas for another piccy or two?

[scannon]

Here are closeups of the block and the block side of the head gasket. If you look closely you can see that between the cylinders there is a complete line of the black paint between each pair of cylinders. Part of it is on the head and part on the gasket. I don't think any would be any paint left if combustion gases were passing through there.

Every blown head gasket I can recall seeing had obvious flame tracks on it if it wasn't completely burned away between the cylinders or a between a cylinder and a water port. There is nothing like that on the head, block or gasket.

I'd love for it to be a blown head gasket. For now I'll have to put a new gasket back in and see what happens.

[bsimon]

The closer pics are great. I'd have to agree with you. I certainly don't see the kind of marking I would expect from a blown seal ring in the gasket. I suppose it could be a quite subtle leak that we've not seen before in our experiences.

I don't have any other ideas. You might want to take a closer look at the cylinder liners for micro cracks. Is this engine one of the later alloy block versions?

The only other way to Siamese the cylinder breathing would be through cracks in the head or broken piston rings. If the piston rings were knackered, I'd expect you'd have seen a lot of oily gradoo collecting in the oil breather/catch can system. Did you happen to monitor any outflow?

Might be time to give Keith a bell and see if he's experienced a similar anomaly.

[Jon W.]

Have you checked the head for warping?

[scannon]

The closer pics are great. I'd have to agree with you. I certainly don't see the kind of marking I would expect from a blown seal ring in the gasket. I suppose it could be a quite subtle leak that we've not seen before in our experiences.

I don't have any other ideas. You might want to take a closer look at the cylinder liners for micro cracks. Is this engine one of the later alloy block versions?

The only other way to Siamese the cylinder breathing would be through cracks in the head or broken piston rings. If the piston rings were knackered, I'd expect you'd have seen a lot of oily gradoo collecting in the oil breather/catch can system. Did you happen to monitor any outflow?

Might be time to give Keith a bell and see if he's experienced a similar anomaly.
This engine has a cast iron block and aluminum head. Visual inspection of the cylinder walls didn't reveal any cracks no does the head show any.

Oil was down about a half quart, most of which was in the catch can. This is normal for this engine on a track day. No lumps or crud in it when I emptied the catch can into the recycle jug.

I haven't checked for a warped head yet, Rob is dropping off a good straight edge in the morning. If I don't find anything I will put in a new gasket, get it running and buy a kit to do a full leak down test. The head gasket alone is a little over $70 from the dealer with a club discount. I thought NAPA might be cheaper but they want $90+ for theirs.

I've been talking with Bill Cardell, owner of Flyin Miata and he has pretty much the same thoughts we are seeing here on the forum. He uses factory head gaskets on his engine builds and never has a problem with them. Neither of us have heard of a blown head gasket on a Miata but I'm sure it must have happened in the past.

[scannon]

I checked the head and block for flatness and everything is within tolerance per the factory service manual. One spot is .005" while the spec is .006". Of course, it is in the worst possible place, the divider between #2 & 3 cylinders on the head. However, there is absolutely no indication of leakage through the head gasket at this point.

Now I have to decide if I want to do a cleanup cut on the head or live with it. I really do not want to up the compression ratio since I am running a turbo with the stock compression ratio.

Any opinions?

[Hank]

Can you deck the head (flat) and run a thicker gasket?

[scannon]

Can you deck the head (flat) and run a thicker gasket?
If taking off only .005" would do it, the increase in compression ratio would probably not be a big issue.

I recall some thicker gaskets being available but also recall they were very troublesome.

I am going to put it back together with a new OEM gasket and see what happens. If that doesn't fix the problem and I cannot find anything else wrong I will just swap out the engine for the spare and use this one to build up a proper high HP motor with all the forged internals and such. Should be able to easily get 350 - 375 hp on pump gas with a built motor.

[scannon]

An update: I got the car running yesterday with a new head gasket. After warming it up I ran a compression test with a friend's gauge. This time it read 125, 95, 95, 140. My old gauge is in the garbage can. :(

The engine runs fine and hasn't overheated so far but it was only in the high 80s today and of course, nothing I can do on the street will put the heat stress on the system like a track day does.

It runs fine although stumbles a bit before it idles when I come off the throttle. I adjusted the idle bypass screw but couldn't get any change in idle RPM. I'll tinker with it a bit more to see if I can fix that minor problem.

I'm going to leave it as is for the time being and plan on doing a build up of my spare engine with forged internals and maybe some head work this winter.