HELP! Fresh Engine Rebuild Dumping White Smoke

[rmlamp]

Alright so I just finished my TT swap and got it started up last night. I ran it for about 20 minutes and it ran great. The engine has a fresh rebuild and everything was running perfectly yesterday minus a small oil leak which I have addressed. I started it up this afternoon after getting a few small things done and now it's dumping white smoke out the tail pipe. Of course this usually means a blown head gasket. I used genuine Nissan head gaskets when I rebuilt it so it's hard for me to think this is the cause. I went ahead and drained the oil just to check for coolant and there was none. I did notice the water pump is leaking but other than that there are no leaks. Any ideas? I really don't want to have to pull the b**** back out if I don't have to. Thanks everyone!

[everpresentnoob]

What do your plugs look like? you can test your coolant for Exhaust Gasses.

[rmlamp]

The plugs are dry but I pulled the radiator cap off and it just gushed coolant everywhere. Not sure what would have caused the hg to blow when the engine literally had 30 minutes of running time. Any ideas?

[elecfus]

when you say it's smoking from the exhaust pipe, they have two. which one? the tailpipe corresponds with the cylinder bank on the opposite side of the engine because of the crossflow design. you can get an idea of which side of the engine to diagnose based on this.

what boost did you run? the water pump doesnt connect to the combustion chamber at all unless it tears through a melted cylinder wall or head gasket so a leaky water pump wont have any effect on exhaust gasses unless you run low on water or its so old that it isnt pumping water properly. always a good idea to run the engine out of the car and fix any leaks then. it could have overheated and warped the heads.

my thinking is that the heads may not have been installed properly. the engine ran fine, heated up then settled back into place slightly warping, letting a small leak form between two passages.
when you rebuilt the engine did you surface the head and block? did you use the correct torquing procedure, new head bolts and seals?


what does your water look like? what does your oil look like?

this can also be caused by a bad seal in the air intake plenum area. there are so many parts with water lines so it will run in japanese snow, it can leak into the air intake not to mention the hassle of a full plenum pull with all those pipes connected. have you done a coolant bypass or do you live in a place that gets very cold?

[rmlamp]

Both exhausts are pumping it out. As far as the heads, I did not resurface them. I cleaned the old gasket off of them and replaced the head gaskets and torqued them down per the fsm. I reused the arp head studs that were on the engine.

My oil is clean, I drained it and there was no evidence of coolant at all. The coolant is the same, no evidence of oil.

I didn't hit any boost, just held it at 2000 rpm until it warmed up to operating temp and then shut it down.

It sounds like your thought on the resurfacing may be the cause.

[elecfus]

always a good idea. it only runs at about $50USD per surface which is far less what you need to pay each time you replace a head gasket+ o-rings, seals for everything and days connecting everything. with an iron block and aluminium heads you can usually get away with only doing the heads in an NA but with the high compression in a turbo its just not worth the risk.

[elecfus]

even though the head bolts are "reusable", they can deform so it's a good idea to replace them as well and you might as well since they need to come out to be resurfaced. as far as replacing parts goes, i guess its just a matter of how much you value your time and if it's worth avoiding another plenum and head pull to throw money at it.

once the heads are off, you can take a straight edge to the block surfaces and shine a torch at the other side, if any light comes through the edge, it needs resurfacing. try it from a bunch of different axis, diagnonally, lengthways, all around the block. on a daily driver 4 banger i dont care about I can get away with just sanding any eccentricities flat but this is bad and nobody should do this.

[everpresentnoob]

once the heads are off, you can take a straight edge to the block surfaces and shine a torch at the other side, if any light comes through the edge, it needs resurfacing. try it from a bunch of different axis, diagnonally, lengthways, all around the block. on a daily driver 4 banger i dont care about I can get away with just sanding any eccentricities flat but this is bad and nobody should do this.

Ha Ha. Glad Im not the only one who has done this. Di this to my old Honda with V-Tick and it ran for another 85000 until my Niece let someone fill it with Diesel oil instead of normal Mobil 1...

[rmlamp]

I'll do a compression test and figure out what cyl it's on. I was hoping it was just burning coolant off the exhaust because the car the exhaust came off of had a blown head gasket and filled the cats with coolant. But when I start it with the radiator cap off, it blows coolant out the radiator. Looks like another engine pull is in my future.

[elecfus]

generally when people say a full engine rebuild they mean more than a head gasket change. where did this donor engine come from? it sounds like you bought a melted engine. head gaskets fail but they fail instantly when the coolant system fails. that leaking water pump is probably what killed it. before spending any more money on it, you need to know what is salvageable. take the heads with everything in them to a shop and have them run a leak test. its not really possible to check for porosity or cracks without their specialist equipment. then strip the block, keeping the crank, pistons and bearings in and take it in for a leak test. they will also do other basic checks like to see if your cams are out of round and will just kill the engine again.

the problem with a diy engine build is that it's pretty much impossible without a machine shop because engines use solid metal to metal bearings and the journals, that is the surfaces that contact, need to be machined to match perfectly to reduce friction then they wear in together and replacement means machining those surfaces again so its just easier to have a machinist do all that work then fit it together, something they need to do anyway to check it actually fits properly.

[rmlamp]

By fresh rebuilt, I mean, it has new oversized pistons, rings, rod bearings, main bearings and all new gaskets. So it is a complete rebuild. The block is an extra I had sitting around the house, not the block that blew the first head gasket. The block was bored and honed by a machine shop. Any cracks would have been detected at that time. Additionally the heads came off the NA engine that this one replaced. Pretty sure that the resurfacing of the heads may be the problem because the first run was flawless. Like elecfus said, maybe the settled wrong after it cooled down. I followed the fsm ever step of the way. The rotating assembly is not the issue here.

[elecfus]

oh ok, you know what you're doing then. some people just swap parts until they run out of money. some mechanics just swap parts until the customer runs out of money too i suppose.

in that case it could be as simple as needing a new radiator cap if its not venting and bleeding the vapor lock in the cooling loop. there's either a sensor or a bolt at the top of the loop that you loosen off until coolant starts dribbling out. with the exhaust having been wet it may just take some time to bake it off.

[rmlamp]

I'm fairly certain that it has to be a head gasket because with the radiator cap removed, it gushes all the coolant out.