by v7guy » Mon Nov 25, 2013 1:03 am
I'm pretty troubled by a lot of the info in this thread. It's like a big beacon of WTF flashing in our otherwise relatively calm sea of good tech, self correction, and healthy debate and banter.
As mentioned, the milky oil could just be general condensation. The stuff in the tail pipe could just be an accumulation of orange clay dust. With that said I think it's probably a blown/seeping head gasket... the previous explanations are probably right, but I've been wrong before.
First step is to replace the thermostat housing that is leaking, then recheck the pressure on the coolant system. If you're still getting a leak the coolant is going somewhere and it's probably the head gasket given the info we have. Secondly, do a compression test, you say you've got some orange deposits in the resonator that's commonly associated with dexcool being burned and shoved out the exhaust (per dave? lol) and you also have milky oil. All signs point to oil and coolant mixing. One of those cylinders should also show a leak like the coolant system did. If you determine that it's the head gasket, I'd just replace it.
Concearning motor replacement. With any motor you get you run the real chance that it was abused/neglected. Unless you open it up and at least check the bearings with plasti gauge, verify the valves seal and the motor is in generally good shape you're tossing the dice. I've tossed motors in and things were great, and I've tossed motors in that spun bearings 3 months later. If you're going to replace a motor and not check everything out, don't be surprised when it self destructs. You only have yourself to blame. You decided to roll the dice. With that said, if you're going to tear down a motor to check the bearings and make sure everything seals and is clean, then you've already spent more than what it would cost to swap out the ole head gasket. As MikeKey likes to occasionally remind us, sometimes the solution that is the cheapest isn't really the cheapest in the long run. We benefit from spending a little bit more up front and saving a lot in the months and years following.
I can say that if the oil and coolant are mixing you likely have weeks or a few months left on the motor. The coolant leaking into the motor will fairly quickly destroy the bearings on the crank and rods and you'll get a hell of a knock out of nowhere that rapidly gets worse and worse over the course of a few dozen miles. I've experienced this first hand in my younger years and with friends. So know that I speak from experience.
In addition if you let it overheat... and realize that the temp gauge on your dash is basically nothing more than an idiot light. You're likely not even going to be able to salvage the motor because of a cracked or massively warped head in addition to the crank and/or rods kissing the bearings. At that point even 2500 for a used motor is worth it, but I would still suggest at least using some plasti gauge to check it all out first so that you don't risk having to go through all this again.
Speaking of warped heads (and blocks)... what the flying frack is going on here?
I'm going to go out on a limb here and say that engine blocks don't generally warp even if they're aluminum. After reading that comment I spent a few days searching out on the web (because I thought maybe I've missed something big all these years) and I couldn't find a single example where that was the problem be it from toyota, honda, GM, ford etc. Some questions started out that way and then it turned out the head was warped, but c'mon guys. This should have been beat down and dispelled the minute it was mentioned. If we're talking about core shift, ok, I can get on board with that. Modern engines don't seem to have a problem with it though. We're talking BIG power to get there. Older small block chevys need 1500hp or so to see core shift unfilled, the LT1 in my firebird even if it's unfilled needs about 1200hp to experience some core shift. These are all old cast iron blocks though. If you want to go to aluminum, you can look at the LS family of engines that pretty commonly see 1000hp+ with no issues at all, they don't even need a partial fill. Then just in case you want to have more power in a dead nuts reliable package GM and a few others offers a cast iron block to get you even more cubes and hp ranges that are undriveable on the street. Even Toyota with their long thin JZ series engines (1 and 2) didn't have any real issue with their aluminum blocks warping. Don't thin for a second I don't recognize the difference in block archetecture and the impact that has, comparing the old SBC to the LS family isn't even really fair, but it's the comparison we have to work with.
Keep in mind that there are some really strong indications that GM had every intention of throwing a turbo on these engines and the idea that a little overheating would cause the block to warp is fracking rediculous. Don't get me started when big money is involved where top fuel is running cast iron blocks to channel 8000+hp or where F1 is using the aluminum block as a stressed member that sees 5gs from the suspension and has the entire motor weighing 210lbs that displaces 214ci and makes 720hp at 18000rpm.
Yes I can provide multiple links to back up all of these claims. Most will come from LS1 tech and the LT1 comments will come from when george baxter was pushing the LT1 and then from the guys over on LT1tech. SBC chevy examples can be found everywhere. Toyota references are easily found on the supra forums and the Ford proof comes from the ford guys trying to show their shit isn't garbage. The guys that have been in this game for a while know exactly what I'm talking about.
Speaking of warped aluminum heads, yes, it does happen. Yes they can be resurfaced and made alright. The long head of an inline 6 motor is more apt to warp than a v6 or a v8, unfortunately it's just the nature of the beast. Some motors are more prone to it than others. Some motors are even a replace the head and forget about it type of deal. I havent' seen that our motor is a problem motor though.
If you're going to just let it ride get the money for a new motor ready or get a motor ready to swap in and know it's in the near future.
build thread All things in moderation, including moderation.
Some people never go crazy... what truly horrible lives they must lead
Thought I had to go inspect the truck... 
