Tensioner woes

The 1984-1987 (and 1989 Turbo Trans Am) engines had something that was relatively new to GM in the 1980s: A serpentine belt with a tensioner to drive the accessories. All the other G-Body powerplants (305 V8, 231 non-turbo V6, and the 4.3L V6) used multiple V-belts, with the tension set by feel.

The Grand National, with its fancy fuel injection and turbocharger, required something new. So, instead of a bunch of V-belts, it got an inch-wide serpentine with a tensioner to maintain tension on the belt instead of prying at accessories with a screwdriver.

This was all well and good, until my tensioner started making noise. Terrible noise. And it wasn’t the bearing in the tensioner pulley, no. the spring-loaded tension mechanism was popping and grinding and making a terrible racket. It needed to be replaced.

Problem: they don’t make it anymore. GM discontinued it. All the parts store no longer had them in stock. Turns out the tensioner assembly was unique to this engine, so it’s NLA. Thankfully, the good people at White Racing has created this new billet tensioner to replace the discontinued stock unit. It’s expensive considering the OE tensioner used to sell for $60, but this is an old, niche car. Gotta pay to play.

So I got one.

New tensioner on left, old and busted on the right

The first thing you notice is it’s shiny. The second is the massive amount of metal around the bolt holes compared to the stock unit. Where the stock unit has thin cast-in gussets, this new piece has been machined leaving as much material around the bolt holes as possible. This was done to alleviate a nasty habit the stock pieces used to have: they’d break. A popular thing to do with the Buick V6 was to put an eyebolt through the alternator, then hook that eyebolt to a ratchet strap that was attached to a hole in the frame. This kept the engine from rocking over to the passenger side and breaking the driver side motor mount. The problem came when people started making big power, all that force got transferred through the alternator case to the tensioner (which the alternator attaches to). The tensioner would then break. Not good. This tensioner is manufactured with a lot more metal hoping to avoid this situation.

Installation was pretty straightforward. Disconnect the battery, take the belt loose, get the intake tube that runs from the MAF to the turbocharger out of the way, unbolt the alternator and swing it out of the way, then remove the two remaining bolts to pull the old tensioner. Installation is reverse of assembly.

After installation, all of the undesirable noises and vibrations that had been coming from the front of my engine are gone. That includes not just the popping, but a persistent click that I had assumed to be a lifter. It was the tensioner all along.

Positive Ventilation

Turbocharged Buick V6 engines are famous for many things. One of them is puking oil out of every possible spot when the engine is under boost. They blow the dipstick tubes out. They force oil past the rear main seal. They spray oil out the valve cover breathers.  Mine even was forcing oil out of the PCV valve grommet under the intake plenum. They can be a huge mess. Even my newly rebuilt engine is doing this. It’s blowby. Gas getting past the rings when the engine is under boost. My first few autocross events, I was coming into the grid smoking after my third run from oil escaping the valve covers and pouring onto the exhaust. It was embarassing, it made a mess of the lots we race in (BAD), and made a mess of the engine compartment. I have been determined to fix it. After several attempts, I think I’ve nailed it. I’ve come up with a system using two catch cans and an industrial strength check valve. It goes a little something like this:

In this first picture, you see the passenger side of the intake manifold. Down underneath the plenum is an OEM PCV valve. The Goodyear hose runs to a catch can bolted to the side of the intercooler, then back up and through that brass check valve. The check valve is rated at 400psi, and is there to prevent manifold pressure from getting into the crankcase when under boost. Without that check valve, positive manifold pressure would easily overpower the OE PCV valve and pressurize the crankcase, which forces the oil out and makes a mess.

Now, the stock set up simply had a hose running from the PCV valve to the PCV inlet tube you saw the check valve attached to. The catch can keeps oil from making it to the check valve and gumming it up, as well as keeping the oil out of the intake tract.

But, there has to be another part. The stock PCV system had a vent in the passenger side valve cover that was connected to the turbocharger inlet. That set up mostly worked, but once you turn up the boost, that single vent simply isn’t enough. I’ve added a second vent.

Instead of one vent line, I ran two. Each valve cover has a Mr. Gasket breather cap on it and a 5/8″ line coming off of it. The lines go into a tee just behind the alternator, then run to another catch can.

From this catch can, we run out to a fitting that’s been screwed into the inlet pipe ahead of the turbo but behind the mass airflow sensor. This is important and I’ll explain.

PCV systems are basically a tuned leak. A port on the intake manifold provides a vacuum source, and a vent in the valve cover/intake tract provides a source of fresh air. Engine vacuum draws air into the vent, through the crankcase, and into the intake manifold where the crankcase vapors are burned in the cylinders.

In a computer controlled vehicle, this poses a problem. If you vent to atmosphere, say as if you’d used an open breather element on the valve covers instead of the closed ones I used, you would get extra oxygen in the cylinders that hadn’t been metered by the MAF. On a Buick using the stock computer, this extra oxygen is detected by the O2 sensor, and the computer adds fuel. In the Buick’s case, it adds WAY too much. So much that it washes out the rings, contaminates the oil, and eventually ruins the bearings. I didn’t want this to happen.

So, the vent is plumbed into the intake tract after the MAF. This ensures the air entering the crankcase through the vents has been metered, so when it shows up in the intake manifold via the PCV valve, the computer has already taken the air into account. It keeps the mixture correct, and doesn’t kill itself.

Under boost, the check valve on the manifold side closes, and the turbocharger inlet should draw out the crankcase gases via the breathers. In all cases, pressure should not build up inside the crankcase. It shouldn’t leak, and any atomized oil will condense in the catch cans and not foul up the turbocharger. All the air in the system goes through the MAF, and all should be happy. So is it?

Yes. In the screen capture below, you’ll see a grid on the right side. That is the Block Learn Multiplier (BLM) table. It’s basically a fuel trim table. If everything is absolutely perfect (70 degrees F, no leaks, perfect engine), all the numbers would be 128.  They’ll vary with conditions (temperature, whether the gasoline is RFG or not, etc.). If you have a vacuum leak to atmosphere, like you would with a PCV system vented on the valve cover to the air, you’ll see BLM numbers above 150, and that’s bad. These are all in the low 130s, which is pretty good.

The PCV system isn’t leaking in air from the atmosphere. I’ve already found a very slight amount of water/oil mix in the smaller catch can after a 20 mile drive, and I’ve got no leaking oil running down the valve covers or collecting under the intake plenum. Preliminary indications are positive, and I’ll report further after my next autocross event to see if this system stands up to competition.

New Seats!

So let’s talk about seats for a bit. Seats are important. Seats keep you in front of the steering wheel while you’re driving. When you turn, seats, combined with the seat belts, keep you from shifting around inside the car. In a crash, seats and seat belts keep you from getting crushed, either by slamming into the rear seat (or the passengers that might be there) or eating the steering wheel. They’re very, very important.

That said, the seats that came in GM products of the ’80s were designed to meet safety standards of the time as well as the desire of the typical ’80s customer for a smooshy, compliant seat. While the Grand National got a decent set of buckets for the period, the foam is still smooshy and the bolsters are set up for a person much wider than me. In a recent autocross, I was using my grip on the steering wheel to keep in place, and the tilt mechanism gave out. The wheel dropped into my lap, and I nearly spun the car out. Not good.

Not too long after that, an acquaintance of mine was racing his Malibu in Lexington, and his entire column failed, and he actually did spin the car. No bueno.

So I bought some seats. What I chose were some black buckets from NRG. I got the pair at Amazon for $299. They’re a ripoff of the Recaro bucket seat you could find in the 2000 Honda Integra Type-R. I picked them because I remember my friend’s Type-R and how well I fit in those seats. Honda made them to fit smaller Japanese customers, not fat Americans, and I fit in them perfectly.

Step one was removing the stock seat, and vacuuming up all the dog hair that was under them.

After removing them, I bolted down the brackets I sourced from Wedge Brackets. These things saved me gobs of time. Fabricating brackets would have taken me hours, and Wedge makes brackets and sliders for OEMs, so I have a bit more confidence in the safety of these in a collision that something I would have made myself.

Next step is getting the sliders bolted onto the seats. The NRG seats came with their own double-locking sliders, so I used those.

The NRG seats showed their Chinese-ness here. The bolt holes for the sliders were covered by fabric, I had to locate them by feel, then use an awl to punch holes in the fabric for the bolts to run through. Annoying.

After that, it was a matter of bolting the seat/slider assembly to the car.

Thoughts on these seats? They’re cheap. The fabric isn’t top-notch. The foam is very firm. In fact, I’ve gotten a new appreciation for how stiff my suspension actually is. The old seats sucked up a lot of the smaller bumps. The lack of squish in the cushions also means I’m sitting slightly higher in the car than I was. I may need to swap out for thinner sliders. The bolsters are fantastic. My skinny posterior fits perfectly and they upper bolsters seem to contain my shoulder and midsection pretty well. I’m able to take corners at speed with just fingertips on the wheel, and that’s using just the three point seat belt. Final verdict on how well they hold is reserved for the next autocross. I’m hopeful I can get away without a harness, because I need my back seat to remain usable.

These are also light compared to the stockers. With sliders, they’re 25 pounds each. The brackets are about 2-3 pounds. The stock power driver seat was over 50, and the passenger seat was close to 40.

But the best benefit? My irreplaceable stock seats are now wrapped in plastic and in the basement, safe from sweat and spilled drinks for the foreseeable future.

Wrapped for storage!

 

A clean garage means a clean mind

After a year of wrenching on this Buick, I’d let the garage get away from me. It was a mess. Such a mess that it really wasn’t a good idea to do any intense work, and I have some intense work planned for this winter. Things like replacing the body bushings, measuring all the suspension points and plugging them into some suspension software to see if I need to fix any of the mount points, a shift kit in the transmission, and new seats/restraints.  All of that requires a clean floor and plenty of space around the car.

After two days of work, I’m happy to report the garage is ready:
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Floor is clean, tools are all put away. I still have stuff on the floor on the sides that I need to get hangers for, but:

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Both cars fit, and I can walk all the way around both of them and open the doors with the garage door shut. My next installment will be a new PCV system for the Buick. A new PCV system that will hopefully end my issues with oil being forced out of the valve cover vents. Stay tuned.