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Commence the biting of nails.

At this point, a vastly oversimplified explanation of engines is in order. In an engine, there are hollow cylinders (6 in our case). They are arranged in banks (2 in our case, and yours too if you’ve ever seen ‘DOHC’ on your car anywhere). These cylinders have valves that open and close to let in fuel and air and discharge exhaust. Each cylinder has a piston that moves back and forth inside it and its function is to, among other things, work in concert with the valves to control the density of gasses in the cylinder. The orchestration of this mechanical dance is called timing and it controlled by a timing belt mounted on timing cogs which control cam shafts running though the cylinder banks. 

A compression test is a commonly performed diagnostic procedure which provides a lot of information about the state of the engine and how well it’s doing its job of producing compression. 

So we did one.

As this is a blog about our experiences learning to work on cars and not a how-to, I’m skipping over all the irrelevant stuff about how a compression test is done (per cylinder: remove the spark plug, insert a special compression testing tool in its place, disable ignition, and turn the engine over for about 5 seconds) and the equally tedious recounting of all the stuff we had to disconnect and/or remove in order to get access to the spark plug banks. The tutorial on how to do this ran 16 pages* and it still didn’t account for the effects California’s special emission standards on engine design. We had some extra mystery hoses that we couldn’t identify for a while. 

Normal compression for this car is spec’d between 115 and 150 psi per cylinder. On a new car, we’d expect compression across all the cylinders to be at the high end of that range, with maybe a 10% psi variance from cylinder to cylinder, if that. If one cylinder were to drop more than about 10 psi from the group, we’d know something was wrong with that cylinder and we’d start investigating the spark plug more closely and worry about malfunctioning values. 

Front bank compression (psi): 180 178 182

Rear bank compression (psi):   92   93   88

What we can read from this is that all the cylinders within a bank are extremely consistent with each other but the banks themselves are wildly different. So, looking at these results, it’s very possible that there’s nothing wrong with the engine itself and we just need to adjust the timing.

Except for one thing.

This engine is classified as an interference engine, meaning that during normal operation, the pistons and the valves occupy the same space at different times. It is only by the grace of highly advanced mechanical engineering that they do not attempt to occupy the same space at the same time. 

Oh, and timing. 

The timing belt is the only thing preventing a piston from shoving itself as hard as it can straight into a valve. So if the timing belt were to break or become ill-adjusted somehow, the engine might bend all its piston rods or shatter all its valves or both. The failure mode is, to put it lightly, catastrophic.

So in that context, these compression results were terrifying. On the one hand, the internals of the valves may well be fine. On the other hand, the timing is way off (and steadily getting worse, because the timing belt seemed to slip a tooth every time we accidentally touched it). So in our quest to determine the state of the engine, we might have accidentally made things a whole lot worse.

*Just to get to the spark plugs. Not even to do the compression test.

State of Play

The last post was all intro, and this post will explain why this car deserves a blog.

We bought a project car. We knew that. It's almost 25 years old, it has almost 100k miles on it, and even a mint condition specimen could stand to use some work if you want to put it on the track, which we do.

This car is not mint. Not even close.

We bought it on a Saturday, in Santa Cruz. Since it was my dream car and the BF is a really nice guy, I got to drive it back home, up Hwy 1, across 84, up Skyline, and over the 92 bridge. Since the A/C didn't work, I had the windows open the whole time. I was in the GT, and the BF was in his 300+ hp sports car following me. It was like a Top Gear special. It was glorious.

I spent dinner alternating between gazing off into space and explaining to the BF how I would completely understand if he decided the car would be too much work and we should sell it and find something else, but that he would have to be the one to make that decision because I had completely fallen in love with this thing and I was willing to do whatever it took to make it run like a dream. He laughed at me all through dinner.

Sunday, I took the motorcycle out on a test ride for an upcoming bachelor party event (which probably deserves its own blog post and I probably won't get to it, so ask me the next time you see me in person) and the BF followed in The Car. Once again, it was sunny and warm and the roads were amazing and twisty and there was no one on them and the scenery was incredible.

And then I pulled over to swap directions and when I looked back, the BF had the hood up.

"I have no oil pressure at idle."

Testing ensued and the conclusion was reached that the car wasn't leaking oil, so he contented himself with theorizing that the previous owner had used the wrong weight oil and mildly revving the engine at stop lights on the way home. Then we put the car up on jack stands and took the wheels off.

That's when we discovered that the car needs two new front tie rods and a new CV joint. Basically, a new front steering rack.

I changed the oil while that was going on (to the correct weight)*.

We pulled the back wheels off and mercifully found nothing wrong there.

Last weekend we did a compression test, discovered the timing belt was incorrectly tensioned (a Very Bad Thing on an interference engine) and found a 90 psi different between the front cylinder bank and the back cylinder bank. This is concerning.

Today, we got results from the company that analyzed our oil sample:

"We're not ready to call this one a lemon yet, but there are some areas of concern. Metals are high, especially copper, lead, and tin (bronze), since they could show bearing wear.  If there's a bearing issue, that could be related to the low oil pressure.  Iron (from steel parts, like shafts) is also high, as is nickel (probably a coating/alloy).  Averages are based on ~2,100 miles of oil use for the 6G72 engine. The viscosity was a bit low for 10W/30, but we don't know if it sheared down or if it was 5W/20 to begin with. The TBN was okay at 3.6.  Check back in 2,000 miles to monitor."

We are desperately hoping this will all be addressed with correctly weighted engine oil.

Tonight, we attempt to manually rectify the timing for long enough that we can do another compression test.

*One of the things I find fascinating about writing is what authors choose to reveal and choose to hide. I can, for instance, just say that I changed the oil on the car like it's no big deal. I do not, just as an example, have to go into all the details about how the oil pan nut is on the side of the pan and how I didn't really appreciate the fluid dynamics implications of that positioning. Nor must you suffer through tedious renditions of hot engine oil shooting out sideways, completely missing the catch pan and drenching my arms up to both elbows. Even the resulting inch-deep pool of dirty engine oil on the visclear we had mercifully laid down can be elided, as can the description of what it's like to clean that stuff up as best one can, generating a small mountain of dirty paper towels in the process, and then having to lie on an oil-soaked piece of plastic for the next hour. Isn't it neat how I didn't have to say any of that?

Harbinger!

I'm back!

I've got a new project and I need a blog for it and I saw this thing kicking around in the corner. So, without further ado, please say hello to the newest member of the household.

Yes, this is now officially a car blog. And that is a 1991 Mitsubishi 3000GT (a.k.a. a Dodge Stealth). The VR-4 edition, of course. The one with 300+ horsepower and all wheel drive and all wheel steering. Its name is Harbinger and the Boyfriend won't tell me why. Apparently I haven't watched enough Battlestar Galactica.

...and no air conditioning and almost 100,000 miles and very cracked leather seats and a 45 lb weight in the trunk masquerading as a subwoofer. 

I have always wanted one of these cars, and always for the most questionable of reasons. It started when I was about 16 or 17. I remember the exact moment. I hadn't been driving long. I was cruising down the left lane of 202 South back home, returning from the KoP Mall (I told you I remembered the exact moment). I was in my Taurus (also a '91, as it happens) and because I was a) new at driving and b) in the left lane and c) in a car so slow and underpowered I would play heavy metal to get it up hills (it seemed to help. I don't know why) I was checking my rearview mirror a lot. A LOT. And there was no one behind me, which was just fine. 

And then, the next mirror check half a second later revealed an inky shadow made out of solid black metal. It was low and dangerous and it had come out of nowhere. So I pulled over to let it past and on the back it said "Stealth" and I decided there and then that it was the most fitting name for a car I'd ever seen. And I really really wanted one.

Fast-forward to a couple years ago when I developed a Gran Turismo habit. For the unfamiliar, it's a video game. You race cars around tracks. With the money you win racing, you can buy better cars. And it turns out that in that game, the 3000GT is a really good buy. It's cheap, it's powerful, and the AWD means it corners like nothing else out there. I spent a lot of fake money and very real time upgrading everything about my virtual 3000GT - suspension, flywheel, tires, turbo, etc. And I won a lot of races.

The thing is, I never really got into real cars. I like them. I like driving them. The Boyfriend has a very nice sports car and I love taking it out. But I haven't owned a car since I moved to San Francisco 7 years ago. And even when I did own them, I never worked on them. I never had the time. But I've always wanted to be someone who is into cars and has owned a bunch and does her own work on them and so on. 

In a household with barely a two car garage and no shop space, these are dangerous thoughts so I kept them to myself. But then the BF said something about replacing his car. I asked him what he wanted, and this happened:

BF: "Well, I've always wanted to be someone who knows about cars. I want to know why I like my car and I want to know what it's like to have owned a bunch of cars and work on them and maybe track them. And the only way to do that is to start buying old cars and working on them."

Those of you who know me will recall that I am an opportunist in the extreme, and I got opportunity served up on a silver platter with that comment. 

So, long story short, we spent a couple weeks on Craigslist and found this thing. We brought it home about 10 days ago and thus began our odyssey into Working On Cars.