Some engine rebuild Q's

HondaDustR · 08-04-2009, 08:22 PM

I've got a used engine coming soon and I'm planning to replace the rod bearings and the piston rings.

1. I've noticed there are 2 types of pistons in the 2.5L, Mahle and KS. I assume they both use the same piston rings, since none of the ring sets specify Mahle or KS only.

2. I'm planning to replace the piston rings and saw that Pelican started selling a set made by Deves and is half the price of the OEM set. They are made in Sweden. I looked up their website and they look pretty reputable. I contacted Pelican and confirmed that it is a complete set for 4 pistons. Has anyone used Deves piston rings and are they any good? Also, when I tore down the seized engine, I checked the end gap on the old rings and it was obviously way too big just by eyeballing it. The normal spec is .20-.45mm and it looked easily 1mm. The cylinders are smooth, but I can feel a slight difference from the ring worn area to the fresh area, but the end gap still looked way off even with the ring pushed down to fresh cylinder. I've read from Lindsey Racing that the OEM ring set often does not give you enough ring to set the proper end gap, especially if the cylinders are worn. The Deves ring set is available in .50mm oversize for the same price. Can I just buy the .5mm oversize and file it down to get the end gap I need, esp. if the cylinders on the engine I'm getting could be in the same shape as the ones I have.

3. Is there anything special that must be done to the cylinder when installing new rings, or do I just set the end gap and throw them in there.

4. For installing the oil pan gasket, they say to apply sealant to just the corners, but I'm so tempted to spread some Curil-T or Permatex right stuff gasket maker around the entire gasket. Is this a good idea or not?

5. I know there's probably a million opinions on how to break in new rings, but I just want a good idea of what to do to seat the rings properly once I get it all back together. I know to use conventional oil, but not sure exactly how to treat the motor for the fist few hundred miles.

Thanks in advance!

cvriv.charles · 08-05-2009, 08:39 AM

I dont have any answers but I do have a good luck and have fun for you. We want to see lots of pics if you can. Thanks.

krystar · 08-05-2009, 09:34 AM

drive it like u stole it. take it to track day. just make sure u warm up completely before going nuts.

HondaDustR · 12:11 PM

I'm just burned up that my camera got broken a couple months ago, otherwise I'd have lots of pictures up.

If you are talking about breaking in when you say drive it like you stole it, is that good? The Haynes manual decribes full throttle from 30-50, slowly coasting down to 30, and repeating ~12 times, to load the rings and letting them cool down. What I've heard over time generally speaking falls along the lines of not to be easy on it, but to vary the load alot, and don't drive it too hard. I would kill to go to a track day, though. Don't know if there's any place close, what I'd have to do to the car to make it track worthy, and it's probably all a little too expensive at this point.

I did find an engine stand at Pepboys for $50, so I'm pretty happy I won't be working on the ground.

As for the oversize piston rings, my dad had a good point that the oversize might be a big enough difference to cause the slightest pinching in at the ring end gap due to a mismatched bore diameter, which could lengthen break-in at best and could wear damage the cylinder due to pressure points, and never quite seal right. I might just take what I get with the standard sized set.

Rasta Monsta · Rasta Monsta's Garage

Quote:

Originally Posted by HondaDustR

Can I just buy the .5mm oversize and file it down to get the end gap I need

NO!

Take your bottom end to a machinist and have the bores and slugs inspected. They will advise you regarding whether you can reuse the pistons or not.

As for track time, your local PCA Chapter I believe is PCA Potomac, and they run at Summit Point and VIR.

HondaDustR · 08-07-2009, 08:11 AM

one thing I found out is the 911 engine rebuild forum has alot of good info...

I did find a link describing proper break-in, and yeah, it pretty much boils down to beating the crap out of it on and off...and change the oil after only ~20 miles. That's good, 'cause I don't know if I would have survived having to drive it easy for 1500 miles.
http://www.mototuneusa.com/break_in_secrets.htm

One thing I am wondering, though, is how rings seat on a Alusil cylinder. The article explains that the crosshatch honing patern acts as an abrasive surface to seat the rings, but it wears down fairly quickly. Do brand new Alusil cylinders have any such patern to seat new rings? What about putting new rings into a used Alusil bore?

cvriv.charles · 08-07-2009, 08:28 AM

God I would love to take my car to VIR. If I was a PCA member in jersey would they make arrangements for VIR? Or would I have to hook up with another region?

Lawrence Coppari · 08-07-2009, 09:17 AM

You have to apply to the region that is hosting the DE. Many different car clubs run there as well as Summit Point, etc..

cvriv.charles · 08-07-2009, 11:30 AM

Thats cool. But I highly doubt I will take my 951 out there to do that. I wouldnt mind buying a nice 931 for that though. Thats would be fun.

Lawrence Coppari · 08-07-2009, 11:39 AM

Why not? My 951 has done over 100 track events in the past 12 years. Most have been Road Atlanta but probably a dozen or so at VIR. Lots of fun.

cvriv.charles · 08-07-2009, 12:35 PM

I know but I just got her so im in that frame of mind where I dont want to beat on her

With some time I'll get in the game

I rode my old bike on VIR. Way fun. I see your from TN. Im in chattanooga right now. Going home back to jersey tomorrow. It's nice here in TN but my car is in NJ so,.... I want to go home

LOL.

John_AZ · 08-09-2009, 02:16 PM

Quote:

Originally Posted by HondaDustR

I've got a used engine coming soon and I'm planning to replace the rod bearings and the piston rings.
Thanks in advance!

I spent some time today planning my next project-rod bearings. Many posts suggest to check the end play of the crank and visually inspect the thrust bearing-one side may wear more. The main bearings do not show wear as often.

Good luck on your project.
John_AZ

HondaDustR · 08-09-2009, 08:31 PM

Quote:

Originally Posted by John_AZ

I spent some time today planning my next project-rod bearings. Many posts suggest to check the end play of the crank and visually inspect the thrust bearing-one side may wear more. The main bearings do not show wear as often.

Good luck on your project.
John_AZ

Yeah. The front side of the thrust bearing on my old motor had worn through to the copper colored layer. I didn't check the clearance on it, though. I don't know if it was normal or if lack of oil pressure contributed to it. I'll definitely check the clearance on mine, but I'm really reluctant to have to re-seal and re-align the girdle unless it's really worn...and a main bearing set is freaking expensive, and so is locktite 574!

krystar · 09-24-2011, 10:31 AM

hey hondadustr, what did u do with the piston gaps after all?

i'm installing new deves rings and looks likes i'm in same situation. the gap looks way too large. have u verified the gap spec is .20-.45mm ?

krystar · 09-24-2011, 12:31 PM

and that 4th hex-like angle oil control ring....where does that go? it looks like it should be on the inside of the wavy ring. oem oil ring only had 3

krystar · 09-24-2011, 12:34 PM

ah straight from manufacturer

Shop High Performance Piston Rings Online - Deves.com

HondaDustR · 09-24-2011, 08:14 PM

Yep, got to love the 4 piece oil ring. Oil consumption is very low on mine. My end gaps ran a bit wide and I just ran with what it was. Compression and oil consumption seemed fine. I can't remember what they were, but they fell within the range of ~0.45-0.6mm. The old ones out of the old motor looked more than 1mm.

Last cam belt change I felt cyl 2 just didn't make quite as much compression cranking over as the rest of them. I hope it's nothing serious. I need to do a compression test and investigate. I do believe one of the fuel injectors leaks down when it sits. Sometimes the motor starts a little hard and runs kind of rough for 10-20 sec. I wonder if fuel washdown is slowly killing it. I need to get off my butt and start making some time for the car!

Too much other stuff going on...(school, work, etc) and I've gotten too used to it always being so well sorted. The clock just turned 180K miles the other day, ~29K on the rebuild. It still hauls, esp now as the air's finally getting cooler.