Page 1 of 2

Why a Diesel?

Posted: Fri Feb 09, 2007 8:53 pm
by 83_maxima
Since I purchased my first Diesel Maxima a couple of weeks ago and have been going through all of the old documents etc., I begin to wonder...what would motivate someone to purchase a light-duty diesel staion wagon in 1981?

Seeing as how I was born in the very same month and year as my car was manufactured, I have no first-hand experience of what times were like then, so I cannot really relate.

All I see are the numbers from the "era". 13% of maxis sold in the us in '81 were diesel - compared to 87% gas. Nissan offered only two diesels (720 and 910) for only a handful of years, as did several other manufacturers. Mercedes and VW seem to have been most succesful in regards to units sold of light-duty passenger diesels.

Then there is the terrible reputaion these (light-duty diesel) cars seem to have earned over this brief period in the late 70s and early 80s.

I am simply curious as to what motivation one would have had to purchase such a vehicle and what advantage they would have perceived during this time. Obviously those that chose the diesel option were in the minority. Dare I ask...why?

My interest in these cars stems first from my love of the G1 maxima (910), but also of compression combustion engines and their flexibility. I would assume that these would not have been the #1 and 2 reasons in 1981.

Please...discuss... :P

Posted: Fri Feb 09, 2007 9:26 pm
by goglio704
1. The gas shortages of the 70's were still fresh in people's minds.
2. Diesel was substantially cheaper than gas.
3. Gassers of the late 70's and early 80's were very convoluted with emissions controls and computer controlled carburetors that didn't work for the most part.
4. Some people just plain like diesels. :D

Re: Why a Diesel?

Posted: Fri Feb 09, 2007 9:39 pm
by philip
83_maxima wrote:Seeing as how I was born in the very same month and year as my car was manufactured, I have no first-hand experience of what times were like then, so I cannot really relate.
During the '70s, the American public weathered TWO contrived fuel shortages. Diesel was always available when gasoline was being rationed. Diesel was cheaper. Anything diesel got better MPG ... a subject pretty much foreign to drivers accustomed to plentiful gasoline priced at $0.25 $0.32 per gallon.

The EPA was throwing its weight around regarding exhaust emissions. For ONLY the emissions measured (CO / HC), diesels did much better, no catalyst nor unleaded fuel required, and diesel design resisted casual user tampering. Of course ANY sane person knew that diesel soot was a far greater health hazard but hey ... that's our government at work.

Between GMs tragic (deliberate sabotage?) diesel passenger car offerings and the success of gasoline / catalyst / electronic feedback fuel management ... diesel ... in the eyes of the public died leaving a bad taste that is still prevalent today.

Posted: Fri Feb 09, 2007 9:46 pm
by goglio704
Actually, the GM 350 diesel wasn't a bad engine by the time it was discontinued in about 83. GM spent a ton of money "sabotaging" the diesel market if that is what they were doing. Several serious redesigns produced a decent motor capable of 200k plus, but it was too late by then. Owner and dealer ignorance also played a huge part in the flop.

Posted: Fri Feb 09, 2007 9:58 pm
by philip
goglio704 wrote:GM spent a ton of money "sabotaging" the diesel market if that is what they were doing. Several serious redesigns ...
GM has always used its customer base as ginuea pigs. "Value Engineering and Research" at your expense. GM will never live down Corvair ... Vega ... the loads of plastic engine and trans parts that should be metal and ... the Oldsmobile diesel. Don't know about their rebadged Holdens (Pontiac and soon RWD Impala).

Let's not even bring up Ford. Car-B-Que is a favorite description.

Posted: Fri Feb 09, 2007 10:08 pm
by goglio704
Last I checked, all automakers were out to get money from their customers, and all of them have screwed their customers from time to time. I always thought brand loyalty has a lot do with accepting the shortcomings of a particular brand. Hard to get used to the bursting into flames shortcoming though, I have to agree with that. :wink:

Posted: Fri Feb 09, 2007 10:10 pm
by asavage
What was said above.

The 1973 Arab Oil Embargo was quite a shock. And it was only the first.

1980, the year I graduated high school, was the midst of a multi-year recession. As noted above, for decades diesel fuel was substantially cheaper than gasoline -- that hasn't been the case now for several years, but diesel's cheaper price combined with greater economy proved a powerful attraction to a segment willing to put up with sluggish performance, cold-start issues, smells and smoke, and the premium cost for the diesel powerplant.

Diesel cars and light trucks were pretty quirky back then, and you had to be something of an individualist to take to one. This is in contrast to today, where diesels are marketed entirely differently than then.

In late '75, my father bought his first brand-new car, a Peugeot 504D Wagon. French cars take even more getting used to (my first car was a 1958 Simca Aronde). His second was a '83 Chev G30 van (diesel), then he bought the '77 MB 240D and later a '93 F250 diesel -- he's still got the MB and the Ford. Yeah, he's an individualist all right, is my father.

In 1977, GM responded to declining horsepower and falling sales figures for its fleet (except maybe the Vega) by doing a half-ass job of converting a very reliable Oldsmobile gasoline V8 to diesel, and selling them as an economical alternative. I have firsthand experience with them, because my boss at the time bought one of the very first Chev C10 (1/2T PU) with the new engine, and we used it in a rental equipment business, with only three of us driving it. I was a teen and drove the snot out of it, and it was fine. That was a plain-jane 1978 model. Next year, boss bought another one but decked-out for his personal use. Both ran great. Had a bit of oil leakage at the valve cover gaskets.

The the next year (1980), he bought a Cutlass diesel for his wife, a luxo version with T-tops. Very nice car to drive, it did have the famous governor failure under warranty on a trip.

The '79 C10 developed a bad vacuum valve at the IP, so his trans wouldn't upshift right. Out of warranty, I fixed it in about 1982.

The first one, the 1978, we sold in about 1980, and the new owner blew two engines in a year. Maintenance. 'Nuf said.

None of those three Olds 350 diesels gave us much trouble. However, ours was not the typical experience. They got good mileage, over 20 MPG in the trucks, around 25 in the Cutlass: they're all very heavy vehicles with poor aerodynamics common at the time.

Head gaskets blew. Crankshafts broke. Injection pumps failed. TTBOMK, that covers probably 80% of the problems. But the word got out: diesels were unreliable.

GM made five major revisions to the Olds 5.7l (350 CI) diesel engine from 1977 to 1985, with the last one being a pretty good engine IMO. As recently as 2001, I bought one (an '82 Cutlass Wagon) for a friend of mine, and it had the GM replacement engine: "TargetMaster" is how they were labelled. It's still running, though my friend just passed away two weeks ago. The trans did die, but that has nothing to do with the engine.

Anyway, the American public's perception of diesel was radically changed by that period. VW and Peugeot and MB had niche diesels in the 70's; GM's entree into the market made the others think that perhaps they could sell their diesels here too, hence the Nissan 720 and Maxima diesel variants. By 1983 though, the news was all over about how unreliable diesels were (even GM couldn't make a good one :roll: ) and sales of diesels in the US dropped off radically. Strangely enough, that was when Ford and Dodge entered with the diesel F250 (late 1983, IH engine) and the D2500 (Cummins). They sold pretty well, as did the smaller Chev 6.2l in the truck line -- a Detroit diesel derivative, IIRC: the 5.7l and 6.2l share no parts.

Hope this helps.

Posted: Sat Feb 10, 2007 6:54 am
by 83_maxima
Thanks guys!

You've helped to clarify this mystery that has been in the back of my mind for a while.

Posted: Sat Feb 10, 2007 6:57 am
by philip
goglio704 wrote:Actually, the GM 350 diesel wasn't a bad engine by the time it was discontinued in about 83. -SNIP-.
The 5.7 diesel engine was FRAGILE. People who drove off cold like you would gasoline engines broke these engines.

350 GM Diesel performance

5.7 Litre Diesel
Used in various GM applications starting with the 1978 model line, the 5.7L 350 Oldsmobile Diesel wngine was the first domestic Diesel engine offered to the public in passenger cars. The Diesel V8, was easily able to acheive "small car" fuel economy in a full size sedan at a pricey, yet affordable price...The economy matched or exceeded that of smaller cars powered by 4 cylinder gas engines of that same time. Since the engine however was introduced to the public too soon, many problems arose after a year or so of use..That combined with poor fuel situations and "lead foot" drivers led the engine through many stages and a number of improvments untill its final year in 1985 when all Oldsmobile Diesel engines where discontinued for all GM applications in 1986. It is claimed to be one of the largest failing disasters in all automotive history, I believe that outlook is not entirly true...the problems that remained up untill its end in 86' where not completly improved, and that is where this all falls into place, in the information listed below on the Oldsmobile 5.7l Diesel V8, 1978-1985
Identifying the differences between D and DX blocks
First, in order to identify the block, you must look on either side of the block, Under the heads, in the center near the freeze plugs. Yes this means crawling under the car if the engine isnt out. You will easily be able to see 350. The Letters D or DX are under 350.

If you have ever wondered what the differce is between the D and the DX block, then here is your answer..

The D Blocks where the First 350 Diesels, They are Identical to the DX block except for the casting numbers..They had regular hydrolic cams, these are the ones that Broke the crankshafts as well as other problems in the bottom end..This Block was made up until 1981 when the DX Block took its place. Why was there bottom end problems?..Simply this, The bolts holding the main caps on, had nothing to grab a strong hold of..they where too short. When building a D block engine, I strongly suggest using ARP Main Studs..they will grip all the threads and hold the caps down tight!..

The DX block features a Roller Cam, reducing wear, as well as 1/4" deeper threads and bolts for the Main Caps..which is what made the bottom end problem come to an end pretty much.
It is not a Bad Block...
The D block isn't a bad block at could always turn it into a DX with the exception of the roller cam (which I am studying carfully), by having deeper threads drilled by a machine shop..other than that, everything else will interchange.
In 1983....
The wrist pins where different sizes..meaning, there are two different wrist pins and bushings.. Engines 1978 through 1982 have 1.050" wrist pins. The 1983-85 motors have a 1.011". Just be sure to order for the correct year to avoid dead ends when building.. I have also been told, The wrist pins from 1978 to 1985 are all the same 1.095. In 1983 they went to a steel backed bushing. 1.200 dia. Which eliminated the bushings from turning. To use this bushing in the 78 to 82 rod you have to bore the rod. I have not yet Compared the Two different types myself..but the bottom line is, when ordering bushings for the rods, specify the year and if possible, take a measurment and have the supplier compare to avoid sending parts back and waiting for the right ones.
Oil Pump Shafts
Oil Pump Shafts..Responsible for driving that oil pump, there was a problem with the 5.7 where the Oil Pump shaft would fail, rounding off the hex on the drive ends or snapping completly in two...Uh Oh!..This obviously means that OEM is not good enough. Mondello Performance has a Billet Oil Pump Shaft (part # OD260)for about $20 plus shipping...Is noticably stronger and weighs more. I belive that Dick Miller Racing carries a similar oil pump shaft. For use on high performance Oldsmobile gas engines, a superior oil pump shaft makes a good little investment when building a motor, or replacing an oil pump...You wouldnt want to loose your engine by trying to save an extra $20 would you???
Head Bolts
Head bolts have always been overlooked on the level of importance, but have played a major role in constant head gasket failure through out the entire production days of the 5.7L Diesel. The head bolts on the early engines had major problems, stretching and sometimes, and most of the time, literally breaking. These bolts would break by either popping the top of the bolt off or breaking in half completly...either way, this would cause that area in the head to loose its clamping force, and naturally, the head gasket would leak...Just imagine installing the heads and forgetting to put one of the bolts in...same thing. At this point, when repairing the engine, only the broken bolts where replaced, others, including the stretched ones that where overlooked, were re-used...which would probrably work just fine on a gas engine..but not this engine. Everyone scratched their heads when the same engine returned 15,000 miles or so later with a blown head gasket.

Some of the joys that go along with running an engine with stretched bolts is the surface of the cylinder head becoming irregular...or in other words, warped. This is explained more thouroughly in the Cylinder Heads back to the head bolts...

In 1982, the head bolts where updated by GM, but still werent any better, the same problems occoured. As GM Goodwrench began remanufacturing the 5.7L Diesel in 1983, the head bolts where again updated...and the problem of snapping bolts seemed to go away...The head bolts would hold torque fairly well untill the timing was advanced to try to achieve better performance. The bolts would then stretch, and the head gasket would eventually fail..but then again, the engine was regasketed and the heads torqued down with the same stretched bolts, that appeared to be ok...

It is very important that the head bolts are measured..they should all be the same length. If any are longer then others, then it is infact stretched, and is probrably the reason of head gasket failure. An engine running after it has stretched a bolt would be the same as loosening one head bolt and running the engine.

I dont suggest the use of OEM head bolts for the 5.7L Diesel, but if you must use them, then be sure to replace them all at the same time..even if they appear and measure out to be ok. The head bolts are supposidly TTY (torque to yeild) bolts..meaning that the bolts cant be re used and should all be replaced in the event that the cyliner head is removed.

To prevent head gasket failure, the timing must not be advanced more then 2 degrees over stock when running with OEM head bolts.
Rocker Arms and Bridges

1978-1983 350 Diesels, had Rocker Arm Bridge pivots that would wear prematurly..thus causing a ticking noise and/or a Back Fire condition...These Bridges are Identified by the Y Underneath in the center..The new ones have a Diamond instead of a Y. This condition usually does not affect smooth operation. If you are experiencing this condition, and your engine is 1983 or before..check the rockers. Remember to replace ALL and not just one.


Posted: Sat Feb 10, 2007 8:27 am
by asavage
I've read that site before (years ago, actually). I don't agree with some of what he's posted [shrug]. In particular, just what in the conversion to diesel has to do with camshafts breaking? The spring pressure sure wasn't any higher. What that about premature rocker wear? Both early and late are still allow pivots, which work well with clean oil, but poorly with dirty oil. And why does he claim that the hydraulic lifter one is weaker than the roller? That engine had been in production since the mid-60's and was very reliable in gasser form.

The crankshafts broke. OK, that's a diesel issue. Ditto on head gasket failures. Recall that until that time, nobody had gone to one-time-use head bolts, and everybody (nearly) reused old head bolts -- as compared with today, with everyone (nearly) having gone to torque-to-yield head bolts.

I agree with the ARP studs recommendation.

Having put a good number of miles behind several examples of the 5.7l, I'd have to disagree that it was fragile. I towed a lowboy and bobcat around behind one for a year and I was not babying it: I found the governor every day. While there are people who could break a crowbar in a sandbox, I was unable to damage any of the four we had, and only minor repairs were needed in all the years we had them (VC gaskets, AT vacuum valve, one IP governor failure). We changed the oil frequently, of course, and never overheated them. But we didn't have any catastrophic failures.

I assume that if we'd owned them long enough, the GP controllers would have crapped, because my experience with the identical $100 controller in my 6.2l and 6.9l diesels show that they are trouble prone, taking out all the GPs when they fail ON. But that's not a mechanical issue.

While there are better diesels available today, back then the 5.7l (after '83 anyway) was a pretty good engine, and I'd still buy another one if one presented itself.

Posted: Sat Feb 10, 2007 11:30 am
by goglio704

You touched on one of the key issues with the 5.7 - overheating. They had virtually no tolerance for it. By the time I got to know them, the ugliest kinks had been worked out, and they were dirt cheap. If you had access to an Olds gas motor which needed a chassis like I did, the diesel was pretty low risk. I got lucky also and found a diesel injection shop run by an ex Olds diesel mechanic who was invaluable to a diesel newbie. I regret letting go of the Olds now. Parts were getting hard to find and gas was cheap. The Internet would have helped the parts situation and fuel is 2 to 3 times what it was.


Did you ever own a 350 diesel? I suspect if you had with your knowledge and mechanical ability, it would have exceeded its reputation.

Posted: Sat Feb 10, 2007 12:11 pm
by asavage
There aren't a lot of diesels that respond well to overheating ;) Esp. if they have aluminum stressed parts. One reason there are still a lot of Nissan diesels running around: cast iron heads.

Posted: Sat Feb 10, 2007 3:31 pm
by philip
asavage wrote:I've read that site before (years ago, actually). I don't agree with some of what he's posted [shrug]. In particular, just what in the conversion to diesel has to do with camshafts breaking?
I recall personally 3 such incidents. The DX got roller followers and a thicker cam casting ... as I recall. Net reduction in torsional twisting.
asavage wrote: What that about premature rocker wear? Both early and late are still allow pivots, which work well with clean oil, but poorly with dirty oil.
The rocker fulcrums were fragile. Easy to break during removal due to the material, brittle cast aluminum ... as I recall. I never replaced a set on a diesel 350 but I have replaced a few broken rocker fulcrums on that vintage 350 gas Olds. Dirty oil ... enemy #1.
asavage wrote:And why does he claim that the hydraulic lifter one is weaker than the roller? That engine had been in production since the mid-60's and was very reliable in gasser form.
I think it is a matter of convienence to say that because for one ... the diesel block had to have physical and lubrication accomodations for the injection pump. I also seem to recall ... that at least the early D block had no oil cooling jets for the pistons (check me). Also, blocks used to be slow cured in sand ... then in the mid '70's "green casting""thin-wall" techniques took over. There was a "learning period" for all manufacturers. Remember all those sand pockets and casting porosity we experienced during the '70's? So things change. Value Engineering is always shaving components. For instance, there's virtually nothing interchangeable from a 1960's small block Chevy V8 and today's small block Chevy.

Posted: Sat Feb 10, 2007 7:43 pm
by goglio704
goglio704 wrote:


Did you ever own a 350 diesel? I suspect if you had with your knowledge and mechanical ability, it would have exceeded its reputation.

Posted: Sun Feb 11, 2007 11:34 am
by glenlloyd
The 5.7 didn't receive adequate development and testing time. GM management told Oldsmobile to have it under the hood by 1978.

In hindsight GM would have probably been better off starting with a clean slate, or purchasing an existing already tested unit.

Its failure unfortunately soured everyone on diesel here in the US. VW didn't even want to use the word "diesel" when it introduced the Passat TDI in 1996 and the Jetta TDI in 1997. They referred to this powerplant as the "turbo direct injection" engine...trying not to use the word diesel.

The downstream impact was brutal on niche market makers like Peugeot, who after 1986 dropped a diesel model for the US.

Had this fiasco not happened we probably would have been on-par with European diesel technology and standards today. The only european diesel powered vehicles coming to the US this year are the bluetec powered MB and the VW Toureg V10 TDI, neither of which I could afford.

I drive diesel vehicles because there aren't a lot of them here in Iowa, they're typically unusual (Peugeot 504, Datsun wagon), and I like the sound of the engine. I'm not scared of maintenance either.

And finally, the diesel can burn bio fuel as it sits now, and is very clean doing that. I'm not confident that E85 is an effective solution and I'm almost sure hydrogen isn't. I'm waiting to see what type of longevity we get from the E85 engines.

steve a