Crossed the Bridge

bus-ted · 08-04-2010, 05:03 PM

Well, I did it. Proud owner of a '91 Ford Thomas with the 7.8L Brazilian mated to a 5 speed with a split axle rear end. 177K on the clock, and paid a whopping $1026 US dollars for it. No blow by, no leaks, clutch is a little soft, so will need a master/slave rebuild. I finally took the plunge and got a diesel. It will be a while before I do any conversion other than ripping out seats.
I'm floating on a cloud.

M1031 · 08-04-2010, 05:45 PM

Sweet score!

Seeria · 08-06-2010, 08:15 AM

Grats! Got a floorplan yet?

bus-ted · 08-06-2010, 08:31 AM

Thanks M1031, Smitty. Timmy- will do, ASAP. Seeria, the only floorplan I have for it in the immediate isn't really a floorplan.
It's going to be a moving van, and I'm going to place a class V tow hitch receiver, so I can tow shorty, who weighs 13,550.
After I get to where I'm going, I'm sure I won't be able to resist the long, intricate process of making it a rolling home. It has to serve me well as a moving van first, though. Years ago, all of my possessions would have easily fit into my shorty, but that's not the case anymore. They're mainly tools, though, so I'm not too hard on myself for it.
Good day, ya'll.

bus-ted · 08-12-2010, 09:56 PM

Well, 848 mile maiden voyage was a success. No major catastrophes. The only glitch was one very expensive fuel filter springing a leak, which was remedied by replacing it with a different type. I'll share what I did, because it might save someone else a similar hassle...
The filter that was on it when I purchased it leaked, and was replaced with an identical one. It's the type with a clear plastic bowl on the bottom with a sensor to tell you through an idiot light/buzzer if you've got water in your fuel. When I discovered it sprung a leak about 600 miles into the trip, a diesel mech. suggested I just replace it with a regular filter, so I tossed the almost $90 piece of junk and replaced it with a $38 plain jane, no nonsense filter. 250+ miles after, and no leak.
A pic of the expensive, crappy filter... and wasted fuel

I guess the most exciting part of the trip was when a mouse crawled out of the crack between the dash and windshield, and in the process of tying to swat it out the window, I nearly killed us by almost running off the road. It could have been a serious wreck, but somehow (almost miraculously) wasn't.

I guess my last thought is on fuel mileage. If I'm doing the math right, I barely got over 8mpg. I was hoping to top 10 per. It does seem that the bus is sluggish in first through third gears, which puzzles me a bit- seems transmission related to me, though I'm not quite sure. It starts getting some real kick from the turbo in fourth, though, and was cruising at 63- 65 in 5th gear, at about 23-2450 rpms. That was with me burying it, then setting the high idle thingamajig as a cruise control. It sounded fine- I don't think I was pushing it too hard. Oil pressure was nice, and temp never went higher than mid -range. Was it just the 'high' speeds causing me to get such poor mileage? Anyone shed some light? I've got a lot to learn about diesel power.
I'll post more pics soon. She's no beauty queen, but she's pretty tough. So far I like her just fine. And look at that engine- almost showroom clean! Overall, I'm pleased as pie. I feel like I got a good deal. The only thing I'm dreading is brake work when it will need it(Lucas-Girling). Out of curiosity, I priced the backer plate assembly... around $500 per. -yikes!

bus-bro · 08-12-2010, 10:07 PM

Sounds like you were running at the maximum governor speed--can be a bit rough on the engine. Seems to be geared low for a 5-speed with a spilt rear, but what would I know.
It would be nice to have a turbo boost pressure gauge installed (to see if the turbo is pumping air to its rated pressure), and I do hope you have an exhaust gas pyrometer.

Seeria · 08-13-2010, 11:21 AM

rofl A mouse! Reminds me of my class A, damn near killed us trying to step on it (drivers side). Bad mice!

yankeflyer · 08-13-2010, 12:27 PM

Look around your final drive ( rear axle ) for an info plate and see who made it Eton - Rockwell - and what ratio - rpm could be a little lower 2000 to 2200

bus-ted · 08-13-2010, 11:43 PM

Well, it's feeling like I'm in over my head as far as diesel engines go. I guess the reason it's sluggish in 1st - 3rd is turbo related.
I need to research it more thorough before I go paying $65/hr. for a mech. to do it for me. Fun, Fun. I'm not regretting my choice just yet, but so far diesels seem more expensive to service, and that's just doing the simple basics. If my turbo's shot, which it likely is, that will just suck.

bus-bro · 08-14-2010, 12:21 AM

One simple thing to check on your turbo is the compressor outlet (air discharge) hoses and clamps, and also check for exhaust leaks before the turbine, if you've got leaks you loose boost and power.

The simple way to check your turbine is to pull the air inlet stuff from the compressor side. Reach in, if you can, and see if the wheel turns without binds (and inspect compressor wheel for damge). You can also try to pull wheel in & out (axial play), it should move just a smidge.

On a diesel, when in doubt change your fuel filters (like when she's a dog). Also, make sure your air filter and inlet ducting is clean/clear. Sometimes a wasp nest or other crap can clog the prefilter ductwork.

Redbear · 08-14-2010, 09:21 AM

The sluggishness should correspond to the engine RPM, not to the gear in use. Diesels have a much narrower "power band" in terms of RPM. My uneducated guess is that you are staying in the lower gears too long instead of up-shifting. Winding the engine up to the redline before shifting may be great for imported sports cars and sedans, but not so much for a diesel engine.

Ever hear a heavily-loaded tractor-trailer take off from a stop light, up-shifting about once every 3 seconds, one second in each gear and two seconds to shift?

I can't find a power curve graph for the Brazilian engine, but for reference I checked the Detroit Diesel web page on a link from Freightliner. The engine that came up had 1550 ft-lbs of torque at 1100 rpm, but less than 900 at 2100 and falling fast. The horsepower rating on that engine is 455 at 1800 RPM, but the curve drops like a rock from that point upward, with less than 325 hp at 2100 RPM. If I extrapolate off the end of the chart (which ends at 2100 RPM), it looks like the HP is down to around 250 at 2200. Your turbo should extend the upper RPM power range a bit and mitigate some of the power fall-off, but that still doesn't make it a sports car.

Maybe someone like Elliot or neverenufhp with thousands instead of dozens of diesel miles behind them can chime in, but in my book the engine itself will either be sluggish in all gears or in none of them. You have to match the road speed with the right gear for good power.

bus-ted · 08-14-2010, 10:58 AM

Thanks Redbear/Bus-bro. The power curve graph you mentioned, RB, is interesting. I think that I need to get some miles and develop my driving style, for sure. I suppose I need a tutorial of sorts for driving it. I can only apply my knowledge of driving gas engines, which isn't exactly enough to carry me over to figuring out the diesel. I was pushing up the rpms just like I would in a gas powered engine, but think I need to try getting through the gears quicker. Nonetheless, a mech. said that the turbo should kick in in all the gears, which it's not. When I first got her, she'd been down for 2 months without being driven. When I fired her up, there was minimal smoke (black), and when I got her out on the highway, there was more black smoke, but it cleared up soon. I was going for "blowing out the cobwebs" for a good hundred miles, then stopped and gave her a full service of oil change, all filters, coolant check, transmission check, lube, and a truck wash. The smoke disappeared and hasn't been seen again since that service. All in all, I'm very pleased. I guess the notion of the turbo going had me scared- and it is worrisome. I hate being at the mercy of a mech., and being clueless myself.

I cleaned off the rear end and found the spec plate- my gear ratio is 4.30 and 6.00. I can certainly live with that.

Also, does anyone know what this is for?

I was kind of hoping it was a door lock of sorts, but I can't figure out how to use it. It's kind of wobbly and doesn't want to move much either direction. Any ideas? Thanks everyone. Viva la Skoolies.

bus-ted · 08-14-2010, 08:03 PM

Regarding the door lock, I figured it out, and it's just that- a lock of sorts. I can't get it to lock yet, though. I'll probably end up doing something else for a lock, anyway, since this type uses the door opening mechanism, which I want to remove to free up space in the driver's area and dash. Oh well, it's kind of a neat idea- never seen one like it before.
Got the road crud cleaned from the undercarriage, locks installed on the battery box and fuel door, and 4 seats removed- all in 100 deg. temps. FUN.

Elliot Naess · 08-14-2010, 08:56 PM

When a turbo charger goes bad, there are usually fiery bits of metal flying out the exhaust pipe and other good clues. Your engine is not a particularly powerful one -- keep the revs down and let it do what it likes to do (which is to trundle along).

Hey.... I'm offended! It does NOT take me two seconds to change gears! (Talking about 18-wheelers now.)

"Thousands" of diesel miles? How about millions? When people ride with me in a car, they tell me I drive like an old fogey. Even when I drive a Corvette. That's just how I'm used to driving. Your bus is NOT a sports car, so it may seem a bit sluggish to you at first. That's how it's supposed to be. It is a Big Heavy Thing.

bus-ted · 08-14-2010, 09:16 PM

O.K.- I admit that I don't know much at all about the proper function of the turbo, and it was suggested that the turbo was acting up after I described the 'symptoms'- the sluggishness getting to speed in the low gears. Should I feel the turbo kick in in all the gears? I feel it noticeably in 4th and 5th, and not so much so in 3rd, but not at all in 1st and 2nd. Is this normal operation? If it is, I can live with it, and I'm even fine cruising at a easy 55 in 5th- I'm used to it. I just want to know my rig is running as it should, and I don't have the experience yet to know.

Elliot Naess · 08-14-2010, 09:38 PM

Since it is normal to go thru the lower gears faster than the higher ones, I'm guessing you just don't have time to register when "the boost comes on", or "the turbo spools up" in the lower gears. If it pulls OK in top gear, there is nothing wrong with the turbo. It does not know what gear you are in.

bus-ted · 08-14-2010, 09:54 PM

Thanks Elliot- that's reassuring. You saying that not only makes me feel better, but re-instills my general mistrust for a lot of mechanics. There are good ones, but it seems there are more that would take advantage of someone's ignorance. I explained the situation to a local diesel mechanic exactly as I did in my previous post, to be told that it "sounds like my turbo's acting up" and should be checked out (to the tune of $65/hr.). I can only assume that either he's dishonest or ignorant, and neither should be tolerated from a "professional". Thanks again.

Elliot Naess · 08-14-2010, 10:09 PM

Well.... There could be some minor issue with the waste gate or something. The hose to the waste gate might be leaking. (The waste gate is a kind'a safety valve that limits the turbo pressure to a safe level.) But the turbo charger itself either works or explodes -- generally speaking from my experience with 18-wheelers.

"Acting up"... is something computer programs do.

JakeC · 08-14-2010, 10:16 PM

I don't see anything here to suggest a turbo issue. If you were having a problem with your turbo not building enough boost, I think you would be seeing a lot of black smoke, but you're saying the black has cleared up, so I think you're fine. Like Elliot said, turbos take a bit to spool up. So in the lower gears, they don't build as much pressure because when you let off, the exhaust flow slows. This is one area where an auto really shines. My allison allows the engine to pretty much pull nonstop, there is almost no hesitation when it shifts.

There is one other thing, though...turbos don't seem to build as much boost if there isn't much of a load on the engine. In the lower gears, the engine doesn't see much of a load, because of the gearing. In the higher gears the engine is able to "load up" more, and the turbo then builds more pressure. This has been my observations at least. Installing a boost gauge and pyro is very helpful, and somewhat educational.

If you want to get a little more from your engine, though, here is an incredibly helpful website from nevrenufhp...http://www.freewebs.com/nevrenufhp/index.htm

JakeC · 08-14-2010, 10:19 PM

Before you start worrying about the waste gate...check to see if you even have one

. Take a pic of the turbo and we'll be able to tell you. I am actually doubting you have one

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