crank scrapper fit?

[AaronGTR]

Ran into another problem tonight. Got the crank bearings all in and installed the crank shaft. Went to install the crank scrapper and it doesn't fit right. It will go in, and it doesn't touch anywhere, but it's got TOO MUCH clearance! Install directions say that you are supposed to be able to move it around slightly to position it, and it should have at least 1mm clearance from the crank. Well, it is a tight fit over the main bolts and won't move at all, and it's at least 4mm away everywhere. That's way more than I would like. How is it going to scrap any oil off if it's that far away? I don't know if they sent the wrong one, but I ordered for a 3400. You can see in the pics how far away it is, and the last pic shows where the hole would need to be for 1mm clearance. Any ideas/suggestions as to why it is like this? Should I even bother installing it? I don't have time to send it back and wait for another one.

[SappySE107]

That doesn't look right at all but that is the same exact scraper as every other one I have had here. Can you take a pic that isn't zoomed in for me?

edit, oh maybe because the rods aren't installed yet. Put those in and see how close the rods get.

[AaronGTR]

Yeah, the rods and pistons aren't in yet because I haven't sized the rings yet. I'm going to do that some time this week (soon as decide what to make the gap), but then I need another person to help me get the pistons in the bores and that might not happen until next friday. Still, that shouldn't really matter should it? The crank scrapper should be getting close to the crank, not the rods right?

[trotterlg]

You need two people to get the pistons in the bore?????????????? Must be a really tight fit! Larry

[Schmieder]

You probably know what your doing but just in case here is a brief description how to install your pistons solo.

Wipe the cylinder wall and crank journals with a white lint free cloth. If anything appears on the cloth, wipe down with oil until perfectly clean.
Lightly oil the cylinder walls and crank journals, bearings. I used standard oil for the cylinders and break in lube for the bearings.
Rotate the crank to BDC for that specific piston being installed
Place hose over the connecting rod threads and have an inch over hang (protects the cylinder walls and crank journals) Some hose have a curl and I have that turn outwards.
Check and make sure the ring gaps are properly positioned and clamp down with the ring compression tool. (leave some piston exposed to guide in the bore)
Gently tap the piston into the bore. It should be easy, any excessive force is bad and will break ring(s). It should take just a few good taps from a rubber mallet. Never use metal to tap them in.
Line up the connecting rod and install bearings, remove the hose and hand tighten the connecting rod assembly to the crank (don't forget the bearings w/ break-in lube)
Torque just right in steps.

Repeat for next piston.


I have a crank scraper from WOT-TECH as well and it fit spot on. Something isn't right, maybe it is being placed wrong. I have a 3100 which is identical to your bottom end (except for a slightly larger cylinder bore).

My crank scrapper needed no modifying and worked like a charm

Like Ben said, get a pic with the entire set up in view. Because the first pic looks like your trying to bolt it up to the block instead of the main bearing threads. But that may be an illusion.

[3400-95-Modified]

That is not the same scraper that I got when I bought mine. Must have changed over time.

[SappySE107]

They had been using a welded piece because the material was too thin, but they redesigned them. The last batch were all the same so I know i have 2 other customers with this design right now. The scraper works on the rotating assembly but is called a crank scraper. It should come close to the rods as they swing around.

[mickaz]

can you use the crank scrapper in a 3500?

[AaronGTR]

For installing the pistons... yes, I have some rubber boots for the connecting rod bolts already. I just had heard that it was easier to install them with two people so someone could guide the rod down from the bottom while the other person held the ring compressor and tapped the piston in from the top. I don't know if the rod bolt covers I have will really keep the rest of the rod off the cylinder wall or not and I don't want to change any scratches. I do have some other hose and tubing I could try and use though. Anyway...

Soon as I get them installed I'll check the crank scrapper again. And yes, I'm installing it in the right place. It's on top of the main caps and under the bolts, as described in the installation instructions. Even if it's close to the rod caps after I get it in, I still think it should be closer to the crank. It doesn't make any sense for it to be that far away when the crank doesn't move around much.

[SappySE107]

If you want it closer, you need the teflon version. There are no 3500 versions because the rods are bigger and the pan is even closer to the rotating assembly.

I have never needed a second person to help me install pistons. Make sure the throw is set for BDC and install, plenty of room to guide it in place once the rings are in the bore.

[Schmieder]

Well, you could take the distance you need to make up and remove that from the far side of the bolt holes. This way you can shift the scraper that much further in. Just use a dremel and shave it down. In this instance, a little working could go a long way.

Example, if the scraper is 4mm away, dremel out 3mm in the bolt holes. But I would wait until the piston and rods are in before you do that.

[AaronGTR]

Well, you could take the distance you need to make up and remove that from the far side of the bolt holes. This way you can shift the scraper that much further in. Just use a dremel and shave it down. In this instance, a little working could go a long way.

Example, if the scraper is 4mm away, dremel out 3mm in the bolt holes. But I would wait until the piston and rods are in before you do that.

Actually I did think about that. I have a carbide cutter for my air grinder that would open them up real fast. Problem is on the middle two holes have enough metal to do that. The metal around the outside pair is pretty thin so there isn't room to remove much to begin with, and I wouldn't be able to get it a whole lot closer. That, and if it ends up being too close to the rods then I can't get it closer to the crank either. Also I'm worried that if I take metal out of the outside holes and make the metal thinner, then there isn't going to be much metal under the head of the bolt on that side and I might unevenly load the bolt and/or main cap or reduce the clamping load.

Personally I don't see why they can't make it 1mm from the rods and 1mm from the crank also. Like I said, it's not like the crank moves sideways (not more than a couple thousandths of an inch anyway), and putting it that far away seems to defeat the purpose. The teflon one is supposed to touch. The steel one should be able to be 1-2mm away and be ok. Not 4mm+. Anyway, I'll see what it looks like when I get the rods in and I'll put more pics up then.

[pocket-rocket]

If anything appears on the cloth, wipe down with oil until perfectly clean.
Lightly oil the cylinder walls and crank journals, bearings. I used standard oil for the cylinders

Not to correct you, but I've read automatic transmission fluid is better for cylinder walls an pistons on reassembly. I also saw one of the guys at JP Machine in Warsaw where Ben used to go assembling an engine dipping the pistons/rings in automatic transmission fluid after wiping down the cylinder walls with it as well.

[torq455]

In the past, I leaned that the thicker the oil the better. Maybe even the STP no smoke additive.

[AaronGTR]

Got the pistons/rods all installed last night and took more pics. Here was how it sat "as is".



The only rod that was actually close to where it should be was #2 (as seen below). The rest where up to 6mm away.



Heck of a gap here.



What I did was leave the hole by the front of the engine alone, and took about 2mm out of the back of the middle two holes and the rear one by the oil pump, so that I could rotate the whole thing in a little on that side. I did end up having to take a little bit of metal off by the #2 and #3 rods then because they were a little too close, but the rest of them are closer now. Some of them still have up to 4mm clearance, but the rest are around 2mm. Much more acceptable IMO.