Hello i am reassembling my 16v kr engine and today i tried to fit the pistons and have came across a problem usually i always fit genuine vw parts but the conrod bolts are now obsolete i ordered aftermarket febi and had them press fitted by a local engine shop so today fitted the crank got everything lubed up with engine lube only to find the main bearing caps will not fit over the bolts to ensure face to face mating has anyone had any issues with these i still have the original bolts and the bearing caps fit with ease
Not had this. Measure them up. Either the bolts need to come back out or the rod caps need machining to suit. Neither option is great IMHO. May have a set of standard rods, if your stuck Jon
Hello Jon, Took your advice and measured the new and old bolts and found a difference To the naked eye the bolts look identical but using a gauge and here are the differences the one with white paint is the new one Roughly 0.2mm These bolts were sold as febi direct replacements using vw part number The existing bolts removed easily with 2-3 taps of a hammer but the new bolt required a lot more force now i am worried have i damaged the conrods (stretched) Jon are your bolts new i will take them if so and thanks for the offer Many thanks This car is testing me it seems one step forward and six steps back
I havent got bolts, new, just used engine bits from a lot of engines I keep to support my motorsport addiction. 8 thou or a fifth of a millimetre. I would consider buying a reamer and hand reaming the cap, bit that's me. I'm not suggesting you do it, its up to you. 8 thou is a lot of interference fit, a very lot. Again, i'm an (ex) electrical controls engineer, not a mechy. Personally, I re-use conrod bolts and dont change them as a matter of course. Not saying you should, but the only motor that's thrown a rod was buzzed (>>8000rpm) by a muffed gearchange by my best mate at a sprint. He no longer drives my motors, LOL Jon
Thanks Jon. I will order a new set from a different supplier With regards to existing bolts VW state that they must not be reused as they are stretch type and with my luck the worst will happen if i reused them can i ask i assume you only reuse them once? Thanks again
The bolts start to work hard at high revs, loading being the square of the speed, not linear, as I understand it. If its a road engine then its not going to spend very long at 6K plus, mostly 2-3K round the doors. What you spend your money on rebuilding your engine is down to you, some manufacturers get a rep for poor/weak parts, not old VW stuff. A lot of these aftermarket forged rods worry me, as they are too cheap.... Jon
I had a similar problem, wanting to fit new bolts to my 16v. I bought new Febi ones as oem equivalents, but my Febi bolts were so tight in the rods that they distorted the holes in my con rods, so nothing fitted and the bolts were at skewed angles. Rather than buy and fit more old rods and bolts, I bought a set of new Pro-Race engineering rods with ARP bolts. Cost a few quid but fitted a dream. If you are happy with the con rods and caps that you have then you could maybe buy and fit a set of ARP bolts on your current rods.
have you used them more than once ? by the way having those replacement bolts fitted has destroyed the con rods on my engine the original bolts actually rattle in the con rods.
Oh dear. well, you can try second hand and have another go with it, but I reckon if you want the engine to rev and last with peace of mind, try the ProRace Engineering rods. Might cost £200 more than sourcing stuff you dont know the history of. But is saving £200 worth it when it lets go?
I've been there with engine reassemblies. It's frustrating when you hit a snag. It seems like those aftermarket conrod bolts might be a bit off-spec. If the original bolts work smoothly with the bearing caps, you might want to replace them with these (www.scrooz.com.au) for peace of mind. Safety first!
ARP do a rod bolt kit, worth the money. I also fitted their head stud kit, really good quality and reusable.
