White smoke on deceleration...
- Thread starter Supra
- Start date
I thought MDC built the turbo, or had a hand in building it anyways. It is an early version of the JT62 bought it through Jeff T. BOV is a Greddy S, which is why I'm limiting myself to only 15psi (17psi once or twice). I've had no flutter or surge probs at either level.
BIG UPDATE>
I finally managed to get my GF to drive my Supra while I tagged behind in another vehical. The smoke is definitely coming from the tail pipe, and it is definitely white, not blue. It is odorless. :3d_frown: Therefore, it is probably coolant... (Although I'm surprized it doesn't have that sickly sweet waterwetter smell???)
To summarize, the more I boost, the worse the problem gets. The Problem is a white cloud of smoke that poofs out the tail pipe delayed after boosting. It does poof a bit between shifts but not enough to see from inside the car. It doesn't smoke at all at idle cruising or light acceleration, so vaccuum seems to be the key.
I absolutely cannot believe the MHG has failed. The deck was surfaced and checked for flat, then hand lapped with a 30lbs. lapping tool, then checked for flat again. I didn't bother to check surface Ra because I used a Titan MHG instead of my usual Greddy but the surface should have been well within range. The Titan HG had rougher/wider Ra specs than the Greddy IIRC. I drilled the rivets out and copper coated both sides of the new MHG. Wiped both block and head with mineral spirits, let it evaporate, set the gasket, then the head on. ARP studs torqued 25, 55, 85 which what I always do. At 500 miles, loosened one at a time and re-torqued to 85 ft/lbs.
The head on the other hand has been through some serious engine failures. I've had this head for a long time and loking back it's been torqued down 3 times, once on a severely overheated motor. It has a bit of money dumped into it in P&P and valve work. Before using it this time, I checked the cam journals for the normal damage and they were like new. Oil clearances mic'ed out fine and the bottom/journals were straight. The head was surfaced and installed on another motor for 5,000 miles prior to being used on my current motor. The bottom of the head was in good shape (no rings,pits).
I'm going to do a CO2 / coolant test when the car cools down today. I talked to Jeff T and he suggested looping the coolant line for the turbo to eliminate that as a possible coolant source. If I have to pull the head, I'm going to send a different head to the machine shop and replace the whole thing.
I do have a Innovate WB O2 sensor. Is there any cause for concern burning coolant past the WB in terms of destroying the sensor? I have no cat conv. so I'm not worried about any problems there.
Will post if I find out more...
BIG UPDATE>
I finally managed to get my GF to drive my Supra while I tagged behind in another vehical. The smoke is definitely coming from the tail pipe, and it is definitely white, not blue. It is odorless. :3d_frown: Therefore, it is probably coolant... (Although I'm surprized it doesn't have that sickly sweet waterwetter smell???)
To summarize, the more I boost, the worse the problem gets. The Problem is a white cloud of smoke that poofs out the tail pipe delayed after boosting. It does poof a bit between shifts but not enough to see from inside the car. It doesn't smoke at all at idle cruising or light acceleration, so vaccuum seems to be the key.
I absolutely cannot believe the MHG has failed. The deck was surfaced and checked for flat, then hand lapped with a 30lbs. lapping tool, then checked for flat again. I didn't bother to check surface Ra because I used a Titan MHG instead of my usual Greddy but the surface should have been well within range. The Titan HG had rougher/wider Ra specs than the Greddy IIRC. I drilled the rivets out and copper coated both sides of the new MHG. Wiped both block and head with mineral spirits, let it evaporate, set the gasket, then the head on. ARP studs torqued 25, 55, 85 which what I always do. At 500 miles, loosened one at a time and re-torqued to 85 ft/lbs.
The head on the other hand has been through some serious engine failures. I've had this head for a long time and loking back it's been torqued down 3 times, once on a severely overheated motor. It has a bit of money dumped into it in P&P and valve work. Before using it this time, I checked the cam journals for the normal damage and they were like new. Oil clearances mic'ed out fine and the bottom/journals were straight. The head was surfaced and installed on another motor for 5,000 miles prior to being used on my current motor. The bottom of the head was in good shape (no rings,pits).
I'm going to do a CO2 / coolant test when the car cools down today. I talked to Jeff T and he suggested looping the coolant line for the turbo to eliminate that as a possible coolant source. If I have to pull the head, I'm going to send a different head to the machine shop and replace the whole thing.
I do have a Innovate WB O2 sensor. Is there any cause for concern burning coolant past the WB in terms of destroying the sensor? I have no cat conv. so I'm not worried about any problems there.
Will post if I find out more...
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drjonez said:
Copper coating in general or copper coating a new MHG? I've coppered a few used MHG and I've yet to have one fail.
I've never coppered a new MHG but it was suggested by several ppl. Some brake/blue stuff was also recommended but I opted away from that. :3d_frown:
I'm thinking that I should just buy a greddy MHG, redo another head and swap them before I get too many miles on the motor. I have thousands of $$$ into this build. The last thing I want is to have bottom end problems because I washed coolant into the oil.
drjonez said:
Will do tonight. I just did the CO2 test (NAPA chemical blue->yellow headgasket tester) and I couldn't get it to change color. Both chambers are solid blue. When I was done - I blew into the end of the tester and the chemical turned bright yellow so I know if there was CO2 present in the radiator, it would have picked it up.
How frustrating. I was sorta hoping for yellow so I could buy and replace the head and my smoke problem would go away. Isn't that sad. :1zhelp:
It's true what they say - "It's hard to quit smoking...". :biglaugh: :biglaugh:
That leaves the engine compression, leakdown test, and bypassing the turbo coolant line...
this is a long shot but worth a look. i was blowing white smoke about a month ago and i was stumped. turned out to be a very small leak from my upper rad hose and while crusing a tiny bit of coolant was getting sucked into the turbo and then being burned off.
it took me like 3 days to find the problem. just make sure you don't have any external leaks that the coolant is landing on the air filter
it took me like 3 days to find the problem. just make sure you don't have any external leaks that the coolant is landing on the air filter
Was hoping that was the problem when the little hose blew. (see above) :3d_frown:
This is the new representitive for my Supra -> :3d_frown:
Many other Supras that I've working on and rebuilt -> :icon_bigg
My Supra's current status -> :3d_frown:
This is the new representitive for my Supra -> :3d_frown:
Many other Supras that I've working on and rebuilt -> :icon_bigg
My Supra's current status -> :3d_frown:
I was just thinking about the last few weeks while on my lunch break and was trying to remember the worse conditions under which I ever re-installed a HG. Turns out the worse I ever did was a few weeks ago. I thought I'd toss up a little story to entertain... I bought a nice 1990 Cressida while rebuilding my engine (~4 weeks ago) from a young guy for $150. He had changed the HG and fired it up see white smoke billowing out, gave up and decided my house would be a good home for it. He told me how he and his friends spent days changing the HG just to have it BHG immediately again. Just for fun, we bought the car, took the car and the guy home with us and my GF and I changed the HG while he waited/helped. Took about 3 hours total.
The block was more pitted than anything I had seen before. Looked like iron colored sandpaper in areas. The head had deep depressions from the previous-previous HG. His "new" HG actually still looked new. Bearing in mind that we bought it for $150 and didn't really care much about it... I took a 3M pad on a high speed grinder and wheeled the top of the block/head clean. We slapped on a copper soaked stock HG and torqued the old factory bolts to 75 ft/lbs. Changed the milky brown oil & filter. So far my GF drove it for 3 weeks straight with no problems.
That damn Cressida is holding together better than my $%*@^ 7MGTE. :biglaugh: :biglaugh: :nono:
The block was more pitted than anything I had seen before. Looked like iron colored sandpaper in areas. The head had deep depressions from the previous-previous HG. His "new" HG actually still looked new. Bearing in mind that we bought it for $150 and didn't really care much about it... I took a 3M pad on a high speed grinder and wheeled the top of the block/head clean. We slapped on a copper soaked stock HG and torqued the old factory bolts to 75 ft/lbs. Changed the milky brown oil & filter. So far my GF drove it for 3 weeks straight with no problems.
That damn Cressida is holding together better than my $%*@^ 7MGTE. :biglaugh: :biglaugh: :nono:
Rich: LOL my worst car repair story was from when I was a kid!
I had a 5L V8 1972 Monaro and had broken a skirt on a piston and didn't have anywhere covered to work on it.
Being young and stupid decided to pull a head drop the pan and repiar it in car in the middle of Winter!
Got it finished but ended up with pneumonia and almost died! DOH!
(many hours soaked to the skin in the cold is surprise surprise NOT a good thing)
I had a 5L V8 1972 Monaro and had broken a skirt on a piston and didn't have anywhere covered to work on it.
Being young and stupid decided to pull a head drop the pan and repiar it in car in the middle of Winter!
Got it finished but ended up with pneumonia and almost died! DOH!
(many hours soaked to the skin in the cold is surprise surprise NOT a good thing)
lol ian... that'd be something to die for :nono:
I'm a bit too fussy to work outside in inclement weather....
I'm a bit too fussy to work outside in inclement weather....
I wasn't able to source a leakdown tester all weekend. :icon_mad: Then, on a fluke a friend from SM called for a minor part and in conversation - he has a leakdown tester. He's going to loan it to me tonight... I didn't bother doing a compression test yet either.
UPDATE>>>
I did bypass the turbo and make two runs. If anything that made the problem worse. There's no shaft play, the turbo spins and spools fine and the smoke didn't go away with the coolant bypassed so I'm ruling the turbo out.
I'll see what the leakdown/compression test shows tonight (barring rain) and see what happens from there.
-Rich
UPDATE>>>
I did bypass the turbo and make two runs. If anything that made the problem worse. There's no shaft play, the turbo spins and spools fine and the smoke didn't go away with the coolant bypassed so I'm ruling the turbo out.
I'll see what the leakdown/compression test shows tonight (barring rain) and see what happens from there.
-Rich
IJ. said:
How about cheapest major repair?
A college kid brought a rod knocking NA Supra to my garage without any cash. I pulled the motor and swapped one rod bearing on the rod knocking 7MGE, reinstalled the motor. Total $$$ spent was $30.00 on a bearing and can of oil pan sealer. :icon_bigg
-Rich87Tx2 said:
I'm with DrJonez on this one and just finished a post on the subject. Read this: http://www.babcox.com/editorial/ar/eb70228.htm
A bit long, but good info on HG failures...the following part on using a sealer is a direct quote:
"Another installer error is using a sealer on a coated composition head gasket. "Some sealers will react with the gasket coating and turn it into goo," claims McKnight. "Our philosophy with Victor-Reinz gaskets is if a gasket requires a sealer, we will include it with the gasket. If no sealer comes with the gasket, it doesn’t need any, and no sealer should be used."
Many people have gotten away with using a spray on a new MHG, but it can (and has) induced a failure too...not worth it IMHO. A stock composite gasket is another story...there is no factory rubber coating to mess up.
BTW...I blew that little hose's brother at the back of the head. Shut down right away, but the damage was done. It got just hot enough to blow the HG :3d_frown:
drjonez said:
The turbo has AN-6 lines for both sides. I unscrewed the inner coolant line from the top of the T-stat. I unscrewed the outer coolant line from the turbo and looped it to the top of the T-stat housing. The flow would be the same as a NA supra. The inner line stays attached to the turbo, but open at the T-stat end. I did one boosted run and let it idle for a long time with the hood open to cool down.
jdub said:
I've always used Greddy HG's + copper spray with great success in the past. This is the first time I used a Titan. I can definitely see the possibility of copper/solvent attacking the rubber HG coating. :3d_frown:
I did manage to borrow a leak down tester from an SM member. I'll do the tests tonight and post where I'm at in the morning. I looked throught he garage and I have 4 heads, 2 of which are NA and the journals are excellent so my worse case senario is sending those heads to the machine shop. <$500 to repair without pulling the motor is something I can certainly handle. The worst thing now is that I have old style ARP studs. It's such a PITA to remove a head in car with those studs. :3d_frown: :3d_frown: :3d_frown:
One other thing...I've never used a Titan before either, but I hear they have a rivet that can interfere with the seal. The Cometic has a similar rivet; it is on the block/head mating surfaces of the gasket and requires removal. Do you remember if there was one on your Titan MHG? If so, that will definitely do it!