Clean coolant in the air intake / induction system

[d3fc0n]

Hello all,

I beseech you all again for information on my 7MGE 1987 Supra. She's been running great, like a top, until recently. She has been a little rough when I drive here lately and the exhaust has been smelling fairly nasty lately.

I first noticed problems when I kept having to add coolant. There are no obvious coolant leaks under the vehicle, and the heater core has been replaced very recently by a reputable wrench. Today, however, when I cranked her cold after my eight hour shift ended I noticed thick white smoke coming from my exhaust. Hm... Head gasket maybe?

I tend to think not. I drove her home and let her cool for a few hours. After she was cool enough I popped off the induction system and found very clean coolant. Maybe it's not leaking from the head gasket? Could there possibly be a seal in the induction system that has failed?

I hope to find out from you knowledgeable folks. Have any of you had this type of problem before? For what it's worth, she's never ever been ran hot. To add, her pistons (and rods and all seals & gaskets) have all been replaced approximately 11k miles ago by the same reputable wrench. Not 100% sure about induction work though. Her head gaskets do leak oil very slowly, but I do plan to replace them at some point.

Can you give me any ideas?

Regards,

d3fc0n

 

[d3fc0n]

I did forget to mention that the oil is clean, no water in it.

 

[johnathan1]

head gaskets? there is only one, and it sounds like you have a BHG, I would start w/ a leakdown/compression test...

 

[mrnickleye]

I'm not thinking BHG. You would NOT have any coolant in the intake system.
I'm thinking ISC, or throttle body. Why you ask ??

Those are the only 2 places coolant can get into the intake system.

The ISC & throttlebdy have coolant lines running to (thru) them. Perhaps one has sprung a small leak, due to corrosion.

You can by-pass them and see if the problem stops. It won't effect the running of the engine to by-pass them, as the coolant is there to warm them up quickly for emissions control.

In fact, I am going to by-pass mine in a couple of months (summer) to allow a cooler throttlebody for cooler intake air, to get a tiny bit more power during hot summer.

 

[d3fc0n]

I'm not thinking BHG. You would NOT have any coolant in the intake system.
I'm thinking ISC, or throttle body. Why you ask ??

Those are the only 2 places coolant can get into the intake system.

The ISC & throttlebdy have coolant lines running to (thru) them. Perhaps one has sprung a small leak, due to corrosion.

You can by-pass them and see if the problem stops. It won't effect the running of the engine to by-pass them, as the coolant is there to warm them up quickly for emissions control.

In fact, I am going to by-pass mine in a couple of months (summer) to allow a cooler throttlebody for cooler intake air, to get a tiny bit more power during hot summer.

I appreciate your post! I'll take a look and see if I can figure out a way to bypass or locate the source of the coolant leak now. Many thanks, I'll let you know what I come up with.

___
d3fc0n

 

[d3fc0n]

I'm not thinking BHG. You would NOT have any coolant in the intake system.
I'm thinking ISC, or throttle body. Why you ask ??

Those are the only 2 places coolant can get into the intake system.

The ISC & throttlebdy have coolant lines running to (thru) them. Perhaps one has sprung a small leak, due to corrosion.

You can by-pass them and see if the problem stops. It won't effect the running of the engine to by-pass them, as the coolant is there to warm them up quickly for emissions control.

In fact, I am going to by-pass mine in a couple of months (summer) to allow a cooler throttlebody for cooler intake air, to get a tiny bit more power during hot summer.

Alright, I have located the ISC. The dealer wants about 500 bones for this mammarjammer. PN 22270-42010. You said something about bypassing it? I disconnected the coolant lines from it and she would not start. I would appreciate any more tips you might have!

Regards,

d3fc0n