As the title states I have a freshly rebuilt D15B7 that out of the blue starting smoking like crazy yesterday. I picked up this car with a blown headgasket back in January and overhauled the engine, below is what was done:

Engine had 320k when I started this

-All new gaskets OEM, entire engine
-New OEM oil pump
-New OEM water pump
-New piston rings
-New bearings
-New timing belt, and tensioner
-D16Z6 OEM mls headgasket
-Injectors Cleaned, balanced, and flow tested
-New Idle control valve
-New fuel filter
-New Plug wires
-New Ignition coil
-New Ignition control module
-New distributor cap and rotor
-New thermostat

-Block was checked for flatness, cleaned, and honed
-Head was milled, pressure tested, new valve stem seals, valve guides, and valve job. It was professionally rebuilt

Basically any moving or wearable part was replaced, I did a complete overhaul on the engine and it was running great. I had no problems the entire time I've been driving it, been getting 45mpg. Out of the blue yesterday when driving home from work it starting smoking out the tail pipe when throttle is applied. It is blue smoke so I know its oil, it also smells horribly like oil. It does smoke a little bit at idle but not nearly as much as when under throttle. I baby this car, it is my daily driver and it never sees above 4k rpm's so it wasn't from abuse.

I pulled the plugs when I got home and Cylinder 1 looked perfect, running just like it should, Cylinders 2 and 3 however were drenched in oil, and cylinder 4 has oil on it as well just not as bad as 2 and 3. I believe this is the headgasket. When I assembled the engine the threads in the block for the headbolt in between cylinders 2 and 3 had rust damage, I cleaned it the best I could but the bolt was still very difficult to thread in and I believe it may not have torqued properly because of this. I will be fixing this when pulling it back apart this weekend, I'm just going to drill it out the rusted threads and helicoil it.

This was my mistake for taking one shortcut because none of the machine shops around me would work on that and I needed to get the car running as the clutch in my other vehicle was beginning to go out.

I guess my question is has anyone seen a headgasket cause severe oil burning? I checked the coolant and I get no bubbles while the engine is running so I dont have excessive exhaust gasses entering the cooling system, there was no evidence of coolant burning on the plugs, and the car operates at normal temperature.

Also I used the mls headgasket because I am aware that the graphite will dry rot over time and cause leaks, also I hate having to clean off the old material left behind from them if you have to pull it apart again. Is there any reason I should or should not use another MLS gasket when putting it back together this time?

 

I wouldn't helicoil headbolts. I've rarely heard of success when people try it. Buy a thread chasing set and gently run it thru the threads with plenty of wd40 or an equivalent. Keep doing this until it goes thru smooth. Don't force it if you hit resistance, unscrew it a turn or so and try again with light force.

As for the oil burning, idk if a head gasket would cause that. Anything is possible. Do a compression test and a leak down test before tearing into it, that should give you a better idea of where the problem is. It's possible the rings didn't seat properly.

 

Doesn't say if new pistons- new rings, yes. Did you engine brake this after it was rebuilt to fully seat the brand new rings? Its not really ideal to baby new rings a whole lot, they need roughed up(throttled up/down under load) a bit to seat. Did you "clock" the rings or did they?

 

I'm going to try to chase the threads before helicoiling, but if all else fails thats my plan. I have helicoiled head bolt threads in the past with great success on customers vehicles. There's certain steps you need to take during the process to ensure that it works properly.

As far as the rings not seating properly, dont you think that would have caused smoking much sooner than after almost 7k miles?

I'm not shooting down your suggestions just trying to be logical and decide if I should just yank the engine completely and tear her completely back down again, or leave it in the car.

I will also be doing a compression and leak down test before pulling it apart.

 

The engine was broken in properly, its been babied since the break in and hasn't given me any problems. I've rebuilt dozens of engines and haven't had any problems with the rings seating properly. And yes the rings were clocked properly, the engine was completely assembled by me, the machine shop only handled the machining.

 

Where does it say you had 7K on it? You've put that much mileage on it in less than 5months? What brand are the rings?

 

Sorry I knew I was missing information, and yes I do drive a lot. I make regular 450 miles trips every other week. The rings are NPR (Nippon Piston Rings) They are an OEM supplier for a few manufacturers and are the same brand rings I put in my MR2.

So to recap, the engine now has 7k miles on it, and up until yesterday they were all trouble free, no problems whatsoever. Then out of the blue this problem popped up last night.

 

Would anyone happen to have a timesert kit that they would let me borrow to fix these threads? I'll gladly pay for the insert that I use and for letting me use the kit?

 

Inspect your valve stems for oil run-down while the head is off. I only use viton material valveseals in mine.

 

Do a compression check. Low compression will cause oil and un-burned fuel to build up in the cylinders. Make sure the injectors aren't dumping in too much fuel in those cylinders. Anything that causes a lack of combustion (poor mixture, lack of compression, lack of properly timed spark) will cause oil and unburned fuel in the cylinders. I had a burnt valve once (no compression in that cylinder) that resulted in a drenched cylinder.
The block should have been decked regardless.

 

Worn valve seals will cause a lot of smoke at startup.

 

You dont deck a block if its within spec, thats completely pointless.

 

I'm guessing you checked the bore sizes before honing? How close to the wear spec were they? Sounds like you reused your pistons, so you're standard size. Is it possible the block should have gotten a slight overbore?

 

Too each their own. I would after 320k. I did and my cheap brand-x gasket is still holding.

 

I don't remember off the top of my head but the bore was definately still within spec, otherwise I would have had it bored over a bit.

 

Well tore it down this weekend, cleaned up the threads in the block on that headbolt, grabbed a new set of headbolts and another HG. Checked the head and block for flatness and both checked out, threw it all back together and everything is golden now. That headbolt looks to have been causing the problem.