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help with mechanic-speak
So I took my car in to the mechanic to replace the motor mounds. It's a '91 350SD, runs great, but has a substantial oil leak (a quart every several hundred miles). He looked at it, and this is what he wrote down on the receipt:
"MAJOR OIL LEAK AT AREA OF THE TURBO CHARGE/AIR INTAKE CRANKCASE BLOW-BY AND TURBO CHARGER SEALS APPEAR TO BE THE CAUSE" He said that it's probably not worth fixing because the turbo charger will run me around $1800 by itself, and then he said something about the blow-by (which I have no idea what that is) and that it'll take major engine rework to fix the leak, and that the more I drive it on the interstate, the worse the engine will get. He says it'll fail eventually, but couldn't say when. Can someone give me some pointers on what he's talking about, especially about this blow-by?
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Gabriel '91 350SD 162k '83 300SD 210k - rear-ended and scrapped '84 300SD 210k - totalled |
#2
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Blow By
The crankcase, that which contains the crankshaft and connecting rods, is the bottom side of the engine - you can see the bottom of the pistons from under there. Compressed fuel and air mixture burns in the cylinder on the top of the pistons. When the rings become tired and worn they allow some of this compressed and burning mixture to leak past and escape into the crankcase. That is called "blow by".
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BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif 15 VW Passat TDI 00 E420 98 E300 DT 97 E420 Donor Car - NEED PARTS? PM ME! 97 S500 97 E300D 86 Holden Jackaroo Turbo D 86 300SDL (o\|/o) |
#3
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when you remove the oil filler cap when it is idling, how much gases come out of the opening? raise idle by moving throttle linkage by hand - does it increase much? Will it cause the oil cap to blow off if you put it on loose?
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'82 300SD - 361K mi - "Blue" "Good judgement comes from experience. Experience comes from bad judgement." listen, look, .........and duck. |
#4
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If he says the turbo needs to be replaced look into having it rebuilt. I had mine done at www.forcedperformance.net
it'll be A LOT cheaper than $1800
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2005 Audi A4 1.8T CVT -Silver/Black "Siegfried" 1982 300D - Silver/Blue "Ralph" -For Sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/119226-1982-300d-sale.html#post852260 1989 VW Diesel Jetta Blue/Blue "Bodo" RIP |
#5
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Quote:
Want to sell it with it's known problem?
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Jim |
#6
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I have heard so much blowby fear from folks then watched their cars run for years with no problems....
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Think Alternative Energy! 300CD '80 (now gone but not forgotten...) |
#7
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Not to be the bearer of bad news but unfortunately the increased blowby is likely a product of a slightly bent connecting rod in cylinder #1. The connecting rod that attaches the piston to the crankshaft can get very slightly bent and wear the cylinder bore a bit oblong thus allowing a steadily increasing amount of oil to get past the piston rings. For some reason, and there are lots of theories but no real certainty why, this is a common problem for your model engine and there isn't a cheap fix. Engatwork is right that the solution may be to drive it until you can't keep oil in it. Try not to rev it any more than you need to and I think your mechanic is right that extended drives will make it wear out faster. You can probably figure that you have a certain number of limited hours left on that engine. Use them wisely.
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LRG 1987 300D Turbo 175K 2006 Toyota Prius, efficent but no soul 1985 300 TDT(130K miles of trouble free motoring)now sold |
#8
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Leak or what
In the original post it was described as a "leak". Is it truly a leak, or is the engine consuming oil. Does it pee and mark it's spot with oil, or is it billowing from the tail pipe? If the turbo seals are leaking, a rebuild would be in order. I am with engatwork, get a second opinion. If blow by is substantial, would it not create a "runaway" situation and just destroy itself? Keep us posted, a leak is a pita, but fixable. A total engine rebuild is costly even if you do it yourself.
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1984 300D Turbo Sedan (Hilda) 272,115 miles..... Anthracite Gray/Palamino Leather, I am 3rd owner 2001 Dodge Stratus (Silver) (wifes) 55814 miles... 1982 280TE Wagon Astral Silver Metallic/ Anthracite Velour 260,512 miles (Eva) 1969 230 Sedan Olive Green/Black MBTex 4 Speed Manual 84,213 miles ???? Haus Frau 2004 Boreem Ninja Pocket Bike Highly Modified 49cc (Ling Ling) Einigkeit und Recht und Freiheit |
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About $10k+/-. Sounds like a rod bender going south.
I would replace the turbo, you should be able to get one for about $1,200 less then he quoted. I am pretty sure I have seen rebuilds in the $600 range.
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1999 SL500 1969 280SE 2023 Ram 1500 2007 Tiara 3200 |
#10
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Quote:
One is blowby. The compression in the engine is bypassing the rings and pressurizing the crankcase. This causes excess oil to be pushed into the breather hose and then burnt by the engine. The second is turbocharger seals. The oil leaks from the turbo and it enters the engine and is burned there. Or it leaks into the exhaust and smoke off. It's not so simple to distinguish between these two cases so he just calls out both of them. It is probably not both of them, but is likely to be one of them. With the history of the 3.5 L engine, most of us would believe that the problem is caused by a bent connecting rod which ovalizes the cylinder and causes massive oil consumption. If the oil consumption increases to 1 quart every 250 miles or less, then you can be fairly well convinced that this is the issue. A turbocharger is unlikely to leak this amount of oil. It's a very expensive proposition to repair this problem as it requires a complete rebuild of the engine. Sorry for the bad news. |
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On the blow by issue, did he give you an actual reading ? The amount of crankcase pressure will give you an idea of how long you have left. If you only have 2" - 3" of blow by, it can make a decent mess, but will not be substantial power loss or signify near death of the engine. On the other hand if it is too much higher.....
I'd be more concerned about the turbo. Long idle time will kill your turbo quicker then higher engine speeds. The center shaft of the turbo floats on oil pressure. The lower the oil pressure the higher the risk of leakage and turbo failure from shaft wobble.
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____________________________________________ 74 240D rolling restoration, daily driver ASE Master Truck Technician I enjoy my work so much I had to buy a diesel to play with ! |
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First, I want to thank you all for the substantial number of responses, all of which are helpful too.
Second, the rod-bending problem. I bought the car in August of '04, and I found out about the rod-bending then, while I was researching it. However, I came to the conclusion that the percentage of cars that have this problem is highly exaggerated. For one thing, there were only a handful of documented cases on the net, which, if it were such a big problem (I heard people saying it was like 50% of them develop it), there would be a lot more cases. For another, I asked my mechanic about it, who had heard of the problem, but had never encountered it, and he's dealt with around 50 350s. He also laughed when I told him about the 50% failure rate, and said MB would've done a recall ages ago if that was the case. So, I bought it knowing that there's a slight possibility of rod-bending. I got a good price on it, and the car is in almost mint condition, and as much a pleasure to drive as any car I've been in. The mechanic I mentioned in the previous paragraph was my mechanic in Gainesville. When I moved here, I had to find a new one, and this guy, whose mechanic-speak I asked you guys to translate, is my new one (Sarasota mechanic). The Gainesville mechanic was hands-down the best one I've ever come across. Professional, knowledgeable, and only deals with MBs. Sarasota mechanic deals with German cars, and after this first, and probably last, dealing with him, he doesn't rank too high on my list. However, he did seem like he was knowledgeable. We talked about the rod-bending issue, and he told me he's only seen it once, and get this, it was in an '87 300SD! Not a 350. And it happened twice, because the guy got it repaired and it happened again. When he was checking for the oil leak, he checked the rods out, and he said he's fairly sure they're not bent, and that my oil leak doesn't have anything to do with that issue. Now, about the $1800 turbo. One of the reasons I didn't care for the Sarasota mechanic is because he seemed to charge more than he should (i.e., $80 for a basic oil change). The Gainesville mechanic noticed the leak when I took the car in for its initial inspection, and he said something about the turbo seals, but he had only looked at it superficially. He said he'd have to look at it further, but he gave me a ballpark figure of $600, which is what a couple of you guys have been saying. So based on that, I think I'm just gonna drive up there in the near future for a day and have him check the car out and tell me his diagnosis. In response to individual posts, Quote:
Quote:
Quote:
Quote:
Thanks again for all your posts.
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Gabriel '91 350SD 162k '83 300SD 210k - rear-ended and scrapped '84 300SD 210k - totalled |
#13
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Quote:
Does it leak a lot of oil onto the ground? Or does it just kinda drip and consume all that oil internally? Also how's the exhaust look? What color and how opaque is it? (as in does it bellow, or a light puff every once and a while) Just because a lot of 3.5l 60x engines had bent rods doesn't mean they all have bent rods. Need to look at all the symptoms first. -Alan
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2005 Audi A4 1.8T CVT -Silver/Black "Siegfried" 1982 300D - Silver/Blue "Ralph" -For Sale: http://www.peachparts.com/shopforum/showthread.php?p=852260 1989 VW Diesel Jetta Blue/Blue "Bodo" RIP |
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Ok, so here's another nail in the coffin for the Sarasota mechanic. Today I'm driving, and I notice this rattling after a while. I pulled over and looked underneath the car, and there's this pan just dragging along the road on one side. I'm not sure what it is, but it's pretty big. I looked underneath the car, and apparently they forgot the put one bolt in, and so after two days of driving, the pan tore in half, and the half that wasn't bolted in is now dragging along the ground! What a great job this guy did.
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Gabriel '91 350SD 162k '83 300SD 210k - rear-ended and scrapped '84 300SD 210k - totalled |
#15
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Gabriel - while you are in Gainesville take it by Continental Imports and get them to look over it. Steve Brotherton (one of the owners) is one of the members of this site and will keep you on the right track with what may be necessary.
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Jim |
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