Franko6
Vendor , w/Business number
I think I have more than my share of engines that we have rebuilt and tested for bent rods. For clarity, I will start at the top.
One of the first checks is to see if the turbo shaft is broken or the compressor wheel is touching the compressor housing. Oil in the intercooler that pours out is a very bad sign of a ruined turbo.
Next, with the injector pump fuel shut off wire removed, and the battery fully charged, all glow plugs out and the vacuum reservoir out of the way, you can test compression. Do not overtighten the glow plug test element. Many of the test plugs are made of brass and will easily strip in the hole. Lightly snugged is all you need.
Run compression until the needle stops rising. It usually will be between 10 -15 strokes. The variation between cylinders should not be more than 10% and the minimum compression would be 390, however, we personally think anything under 420 is relatively poor. The compression on a perfect engine is between 500-515. If it's 490, I would surely be satisfied. Be fair warned, if you have no comparison, gauges can be off and comparative values are important. I'd rather have cylinders registering 450psi across the board than 500 on some and 450 on others.
As for replacement of rods, we have stock replacement rods that we have organized by weight and LENGTH. Unfortunately, not all engines are the same. Although most will be fairly close, if you install rods that vary by as little as .004" in length is to vary compression ratios by .5, when the expected compression is supposed to be 19.5. Just so you know, from the shortest to the longest rod we stock, it's .040" difference.
The other issue we regularly note with piston/ rod assemblies is the variation in weight. Apparently, VW allows 8 gr between reciprocating sets and as much as 12 grams for opposing sets. In other words, if 1-2 piston set weight can be lighter or heavier by almost 1/2 oz. In my feeling, this is a lot and although the engine can run, it runs much more smoothly with balance weighed piston/ rod sets.
As for aftermarket rods, we have such sets in the H-beams we feel are superior, however, if the intent is to reassemble the engine for stock performance, there is no need to use big rods. We can effectively match from our sets of stock OEM rods to suit.
Once it is determined if the compression drop merits cylinder head removal, we measure the piston projection to confirm it is a bent rod. Once confirmed, drop the oil pan (we have some good hints, tricks and tips..) remove the offending piston/ rod and it's reciprocating piston/ rod. Mark for pistons cylinder location. We will balance sets to within .1gr, which is maybe a bit anal, but more than that, because we can. We check pistons for damage, as a badly bent rod can cause piston scarring. We stock sets of good used pistons also.
Then, it's a matter of checking bore dimensions. If there is more than .001 taper, we recommend honing, but not more than .003" from stock bore dimensions. Otherwise, you bore to the next oversize.
Replacing rods is not so much 'drop in', as there can be variations in length, the CRAP rods will not only vary in big-end size, but in taper and length. Tolerance for a well-made rod is .0002", so accuracy counts. If you get a short set of rods, the block would need to be decked. Long rods... you got trouble. You would have to mill the piston height.
As for the Bentley manual, they are the best, but have mistakes for the pistons for a 1.9 TDI engine. The measurements in the book are based on a stock piston of 79.46mm, but almost every TDI we have ever seen, the pistons are 79.44. .01mm = .0004" or roughly .0008" deviation from the book measurements. Again, that doesn't sound like much until your engine burns oil and the rings won't seat.
If we can be any additional help, feel free to contact us. I don't think I would want to do this job under street lights, especially in Alaska. Days are already rapidly getting shorter and although you are more protected as far South as you are, I'd say rain, rain, rain, would hamper your 'outdoor' environment.
Good luck.
One of the first checks is to see if the turbo shaft is broken or the compressor wheel is touching the compressor housing. Oil in the intercooler that pours out is a very bad sign of a ruined turbo.
Next, with the injector pump fuel shut off wire removed, and the battery fully charged, all glow plugs out and the vacuum reservoir out of the way, you can test compression. Do not overtighten the glow plug test element. Many of the test plugs are made of brass and will easily strip in the hole. Lightly snugged is all you need.
Run compression until the needle stops rising. It usually will be between 10 -15 strokes. The variation between cylinders should not be more than 10% and the minimum compression would be 390, however, we personally think anything under 420 is relatively poor. The compression on a perfect engine is between 500-515. If it's 490, I would surely be satisfied. Be fair warned, if you have no comparison, gauges can be off and comparative values are important. I'd rather have cylinders registering 450psi across the board than 500 on some and 450 on others.
As for replacement of rods, we have stock replacement rods that we have organized by weight and LENGTH. Unfortunately, not all engines are the same. Although most will be fairly close, if you install rods that vary by as little as .004" in length is to vary compression ratios by .5, when the expected compression is supposed to be 19.5. Just so you know, from the shortest to the longest rod we stock, it's .040" difference.
The other issue we regularly note with piston/ rod assemblies is the variation in weight. Apparently, VW allows 8 gr between reciprocating sets and as much as 12 grams for opposing sets. In other words, if 1-2 piston set weight can be lighter or heavier by almost 1/2 oz. In my feeling, this is a lot and although the engine can run, it runs much more smoothly with balance weighed piston/ rod sets.
As for aftermarket rods, we have such sets in the H-beams we feel are superior, however, if the intent is to reassemble the engine for stock performance, there is no need to use big rods. We can effectively match from our sets of stock OEM rods to suit.
Once it is determined if the compression drop merits cylinder head removal, we measure the piston projection to confirm it is a bent rod. Once confirmed, drop the oil pan (we have some good hints, tricks and tips..) remove the offending piston/ rod and it's reciprocating piston/ rod. Mark for pistons cylinder location. We will balance sets to within .1gr, which is maybe a bit anal, but more than that, because we can. We check pistons for damage, as a badly bent rod can cause piston scarring. We stock sets of good used pistons also.
Then, it's a matter of checking bore dimensions. If there is more than .001 taper, we recommend honing, but not more than .003" from stock bore dimensions. Otherwise, you bore to the next oversize.
Replacing rods is not so much 'drop in', as there can be variations in length, the CRAP rods will not only vary in big-end size, but in taper and length. Tolerance for a well-made rod is .0002", so accuracy counts. If you get a short set of rods, the block would need to be decked. Long rods... you got trouble. You would have to mill the piston height.
As for the Bentley manual, they are the best, but have mistakes for the pistons for a 1.9 TDI engine. The measurements in the book are based on a stock piston of 79.46mm, but almost every TDI we have ever seen, the pistons are 79.44. .01mm = .0004" or roughly .0008" deviation from the book measurements. Again, that doesn't sound like much until your engine burns oil and the rings won't seat.
If we can be any additional help, feel free to contact us. I don't think I would want to do this job under street lights, especially in Alaska. Days are already rapidly getting shorter and although you are more protected as far South as you are, I'd say rain, rain, rain, would hamper your 'outdoor' environment.
Good luck.
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