2seater

It is easier to clean the evaporator if you also remove the blower motor assembly. That gives two points of access so you can shine a light in as well as see from the top. Also an alternate access for the vacuum.

Aside from the devices used, the information and diagnosis, as well as the conclusions, are very good. Appreciate it.

It looks like the visible tabs hold the lower frame that supports the spring, but the flange itself is one layer. It does look like that lower frame may be too wide to drop in as mentioned. I hope you find a way

You're right, apparently the design changed from the '85 GN to the '86-'87 intercooled models. I wonder if it could be trimmed down approx. 3/8" to drop in? It was an intriguing idea.

I am glad you are doing this experiment, very useful information. Warm oil and cooler water sounds like a good combination.

I wonder about that thing in the rear that is supposedly a proportioning valve, which I did find was unavailable new a few years ago. When I remanufactured all the rear brake lines for my '89, it doesn't appear to be anything more than a misshapen tee? When I re-did the rear lines, I relocated the "thing" to a central and easily accessed location on the rear subframe. I wonder how this would even function? The location is completely off center, so there is a huge disparity in line length and almost any proportioning valves I have seen on other vehicles are at or close to the front? Since this is a three channel as RDG points out, why would it even need such a thing? The rear brakes function purely from modulating the booster pressure while the fronts do get a conventional boost from the assist system. I did not try those brakes in anger after I did the relocation, so perhaps there is some sort of balancing happening that I could not detect in normal use. Buick proportioner vs Thunderbird. Same Teves Mark II, and the T'bird one is still available but is it correct???

I don't think it will be a big issue. Oil temperature is influenced by the coolant temp. but is not the only mechanism that heats the oil. It splashes on the pistons and cylinder walls, bypasses through the oil pressure regulator, bearing friction etc.. Oil is a major contributor to keeping the working parts of the engine cool. In cooler weather, it is better IMHO to get the coolant temperature up to help warm the oil and other reasons. It would be interesting to have an oil temp. gauge and see what the influence the cooling system has.

As far as I know, the t'stat from a Grand National is the same small body design as ours? I had never heard of a 170* design but the first 160* I purchased was from a Grand National vendor in Tennessee before there was anything available in the small body stat. Interesting idea. What I found with the cooler 160* 'stat was a bit better engine performance, way back when, but there did seem to be a small mileage penalty. I do believe the earlier cars went to closed loop a bit later than the '90 that I work with. I would have to check the chip for the setting, but if memory serves, it was in the 140* range.

Yes, there is a check valve in the tee at the firewall directly behind the throttle area. One leg of the tee goes to the HVAC controller and the other feeds to the cruise servo and vacuum reservoir below the air inlet tube to the throttle body. One of those hoses may be deteriorated or possible the vacuum fitting on the bottom of the HVAC controller is loose, located on the far right below the glove box.

There is definitely a ground speed component to the fan operation and have found that in the chip, but I thought the speed was higher than 20mph in stock form? I have no idea how that may affect the testing but it appears the fans deactivate at some particular speed so may complicate the diagnosis?

I believe you are on the right track, and that is my ultimate goal; turn the fluid volume measurement into something everyone can use as a reference. The present standard is good. My intention is to tweak it a bit. The figures I get for the three accumulators I tested convert to 4.56, 6.59 and 6.76 oz. from empty to fully charged at pump cutoff of 2600psi. I listed the capacity at rated pressure of the ball @ 3050psi also but in normal use it never charges to that pressure. This was done just for reference but perhaps is misleading? All of the ones I tested were still operational and the brakes felt normal, however I couldn't pass the brake pump test before the pump turned on. Even the new ball was good for no more than two "pumps". If memory serves, the used accumulators were in the 9/16" drop range and the new one was a bit under 1/2". I wasn't being very critical at that time so the measurements should be taken with a dram of ethanol

It happened to me too, although in a different way. I figure it was boost pressure from the turbo installation that got to it. I think I remember seeing some where that the oem modulator can only take 5-6 psi positive pressure? It drinks a surprising amount of fluid through that line when it fails. At that time I had no catalytic converter and it would stink to high heaven too. An aftermarket adjustable model appears to have a greater resistance to boost.

Good to know that 60* V6 will work too. I believe the module from the Buick 3300, through '93, will not work since that engine doesn't have a cam sensor. That may not be 100% true and the cam input is in the module and not connected or used? The coils should work fine.

The vacuum is a good idea, everyone has one of some sort. I made a vacuum unit from an old two piston automotive a/c compressor and a castoff one gallon bug sprayer jug as my fluid reservoir/catch can. A good shop vac. should be able to pull maybe 8"Hg of vacuum, so that should work just dandy. If run for long, do you bleed in a little external air to keep the vacuum motor cool. Short term shouldn't be an issue. Would work okay to pull fluid through the front brake bleeders too. I know my forearm gets mighty tight pumping that MityVac hand pump when doing that.

I think I see what Barney has in mind and is similar to my thinking. What I was trying to do is get a better handle on the actual volume of fluid that charges the accumulator with the aim of transferring that to a reservoir reference level change. I know we have an approx. standard developed from years of actual experience from forum members and my purpose was to quantify. Part of the issue is the actual shape of the interior of the reservoir with the level gauge is unknown to me and the measuring point needs to be consistent for good confidence in the results. The brake fluid doesn't seem to have much of a meniscus in the measuring cylinder so I would think the surface tension is lower. Water might work fine but the surface tension would need to be knocked down with a couple drops of detergent. I guess I would try alcohol for level testing. If on the car, obviously brake fluid is the liquid of choice.

Yes, as far as I can tell, that would be true. Yes, I agree. I noted the brakes feel more firm with the SW unit. I suspect the pressure depletes less quickly with greater volume so the "feel" is better, but no data to back it up.

I mentioned in another thread that I was going to try to get actual data on the performance of the accumulators I have on the shelf. My test rig utilizes my pressure gauge assembly for testing system pressure on the car, a 500ml graduated cylinder and a used pump/motor assembly. The graduated cylinder is just a cheap plastic Amazon special accurate to +- 5ml with a hose barb tapped into the bottom as the reservoir. I used the same 350ml level as the start of each test to minimize variation. I ran the pump manually with a battery on the bench and stopped at test pressures I chose based on what I believe are close to correct: 1500psi for red dash light turn off, 2000 psi for pump restart via pressure switch and 2600 psi for pump stop. Accumulators A & B are used from my '89 and '90 and C is a new stock one I installed briefly and then replaced with the Spinning wheels larger model. I won't go into the reasons for replacement but there was a clear difference. I ran each test three times but they were very consistent: A: 170ml @ 1500psi, 190 @ 2000 and 200 @ 2600 also 208ml @ 3050 which is the ball pressure rating B: 155ml @ 1500psi, 175 @ 2000 and 192 @ 2600 202ml @ 3050 C: 60ml @ 1500psi, 102 @ 2000 and 135 @ 2600 150ml @ 3050 As can be seen none of them held close to the .250ml @ 210 bar on the rating stamped into the ball. I believe that is the total volume of the ball from rough measurements of the exterior. When testing, the pressure immediately jumped up to close to 1000 psi upon pump start for ball C, which seems to indicate a full nitrogen pre-charge, much longer for the other two. Please note, all of these accumulators were operational and not causing real issues when removed. One more thing, both the pressure switch and ball were just run down by hand without mechanical assistance as the sealing is done by an o-ring, so no need for gorilla force. The one takeaway I found was the amount of fluid contained between 2000 psi pump on and 2600 psi is pretty small but significantly greater in the fresh accumulator: A=10ml, B=17ml and C=33ml I don't have my cars out of storage so I cannot define what the precise fluid level change would be in the reservoir, using the amount of fluid listed above, but less drop is definitely better based on what I found. I should add, as long as there is significant run time, less is better, but a fully flooded one will show very little change in level and a short run time. If there are any suggestions on where I could improve or other types of tests, I welcome the comments.

If the reservoir could be calibrated in some manner, it might provide a valid measure of the accumulator capacity. I know we have an approximate fluid drop standard, but I do not know how regular the interior shape of the reservoir is to fine tune the actual volume change. I know the accumulator has a capacity listed but not at what final pressure that it is measured at. I think I have an operational pump and motor and although it is taken apart at this time, I would believe it should work to make a test rig. I do not have the motor and switch harness but I should be able to power the motor directly and switch it manually while watching the gauge setup I made previously. I'm thinking my head cc'ing burette should work as a reservoir? I know this has been an issue that has vexed us for a long time.

I looked a little online about fuel tank composition and fuels. It appears GM tanks were coated with a lead/tin mix, inside and out or nickel under the coating or a zinc/tin as lead was phased out. Apparently the government mandated a minimum ten year life. There was also statements that methanol reacted or leached the lead or some other component degrading the coating. Later in the article, methanol and ethanol were used interchangeably but they vary drastically in the their reactivity, so I am a little skeptical about all of the info. That said, certain formulations of gas dryer products, such as Heet, do contain significant methanol. The general consensus does seem to be that a fuel tank does have a long, but limited lifespan, particularly with oxygenated fuels. Perhaps the local fuel composition may have some bearing and I know some high density areas used MTBE as an oxygenator although I believe that has fallen out of favor due to other concerns? That is all speculation on my part but just a quick search does reveal there may be an issue lurking.

Not doubting the veracity of the horror story, but if this is an issue, I wonder where the others are hiding? Perhaps this is the tip of the iceberg? I know the fuel lines were changed in 1990 but were there changes to the tank also? It does make me ponder if I should drop my tank and take a look when it comes out for summer. The pump was changed several years ago to a higher flow Walbro and I don't remember any issues at that time, but that was then.

I don't know the level of interior rust but it is hard to beat the oem from a quality standpoint. I thought the tanks were terne coated from the factory, but could be wrong about that. I guess the question is if the tank is the source, or something else, perhaps the filler tube if not from the fueling itself. I guess I would keep the original and coat it but JMO.

I agree that in general the stiffness is based on the bar diameter. If there is a substantial difference in the end links causing the bar to be at an angle, rather than at approx. 90* to the applied force, I would think it would change the effectiveness. I would think, if the bar is slightly high under no load, and it approaches 90* under load, it might be somewhat more effective, and the reverse would make it less effective. The end travels in an arc after all. JMO

I looked a bit more and according to Engine Builder, the castings are the same number for the vin C and vin L engines through '95, although there are small differences such as the pcv vent hole and the '93-'95 vin L vin 1 s/c do use the roller pivot rocker w/aluminum guide plate. The bolt for the rocker is 5/16" vs the 3/8" on the bathtub pivot like ours. It is possible the drilling in the head for the rocker may be relocated some also as I tried one of those rockers and the line up was poor. All have the same 38cc combustion chamber and none have the later, and preferred, heart shape If you are, or have someone good with welding, they could be modified and then recut the seats By the way, some Ford 3.8 pistons will work in our engine, have a much smaller dish, the correct piston pin, and will really raise compression ratio into the upper 10's. E85 anyone?

I read Vizard's stuff with interest as well, but this is no full on workup. Without a lot of work I was showing about 202 cfm with no valve and I am within 10 of that @ .450, so good enough. Average air speed about 260 fps. I agree on the rougher back surface. Polished up I lose a couple cfm. I do not know for certain on what other heads will fit, but I would guess any of the Series I will work. The heads with the tpi style intake have a port for the PCV plumbing, which is all internal, but the hole can be tapped for a pipe plug to use either style manifold. Pretty certain the ports are in the same place and somewhere in the '93-'95 time frame used a roller pivot rocker with standard style pallet tip. They are not a drop in for earlier heads. I would be interested in your results if you ever play with a set.