2 Port head cracked and burning coolant

[Ozzymosis]

I I was hoping someone out there may have some insight. My Supra started smoking about a thousand miles after purchasing it. I could tell it was coolant by the smell and color. The warning for low coolant has come on twice in 9 months, and I’ve put maybe a half liter in both times. I took it back to the dealer and they claimed it was blow by, and slapped a catch can on it. I was a little hesitant to believe that would fix it, but when we started it up no smoke… For a day or so it didn’t smoke like it had before, but then it returned. Trying to take it back to the dealership (Action Auto in Utah) they told me there’s nothing they can do. They told me it’s my problem, and they wouldn’t help me because we are a sale as is state?. This car has been such a headache. I’ve searched for a good local mechanic, but found it’s extremely hard to find someone that is willing to work an MK5. The first mechanic I found that was willing to work on it said the oil pump was bad and needed to be replaced. I had the notorious plastic oil pump that breaks and doesn’t read correctly. So yes he was correct, and I had them replace the oil pump with the updated one, but it didn’t solve the smoking issue. I’ve since tried to contact that mechanic to do a deeper dive into the smoking, but they’ve ghosted me as well. So I continued the search for a mechanic willing to work on the Supra. I did finally find another mechanic, and he did a deep dive into the burning coolant. Like the previous mechanic he said the engine passed the compression test, and the turbo checked out. He also said there wasn’t any contamination in the coolant. He then pulled the turbo and scoped the head and said he found a crack in the 2 port exhaust manifold. I Included photos of the crack, and while I want to trust his assessment I’ve been burned way to many times with this car. He said the whole head would need to be replaced, and quoted me $6,500. I’ve only seen 1 thread regarding this issue, and was hoping for some input/thoughts. Is a cracked head a common issue with these cars? If I did fork out the $6,500 would that solve the issue, or am I going to continue this wild goose chase?

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[lucky phil]

Well it looks like it's cracked when you consider the images and the symptoms but to be 100% sure you could buy yourself a coolant pressure/fill tester which are very cheap to buy and pressure test the system. I've got a ton of experience in boroscoping and it's often very hard to differentiate a hairline crack from a casting joint. , Assuming it's a cracked head then sourcing a second hand head might be your best option if any are available.
The other option might be a complete second hand engine, preferably the later 6 port type which has more power stock but you'd need to get it complete with the turbo. I'm not really a big fan of integrally cast manifolds as it makes for a very complex casting and more complex is more risk for casting defects that may take some time to present themselves as is probably the case here.
There may be some other finer detail issues to consider fitting the later 6 port engine and I'm sure others will chime in on this but from a mechanics hourly rate and hours required perspective a replacement engine is probably a better option.
Phil

 

[Thraxbert]

I admit this looks suspicious to me, too, but you could get a conclusive answer with one of those NOx detector tool things. It will change colors if combustion product is in your coolant mix.

 

[TurboZX10R]

I’ll give you 20k for the car problems and all. Just kidding. I’d send it to a reputable shop, if you don’t know where to start diagnosing. Pm me if you want suggestions.

 

[Ozzymosis]

Well it looks like it's cracked when you consider the images and the symptoms but to be 100% sure you could buy yourself a coolant pressure/fill tester which are very cheap to buy and pressure test the system. I've got a ton of experience in boroscoping and it's often very hard to differentiate a hairline crack from a casting joint. , Assuming it's a cracked head then sourcing a second hand head might be your best option if any are available.
The other option might be a complete second hand engine, preferably the later 6 port type which has more power stock but you'd need to get it complete with the turbo. I'm not really a big fan of integrally cast manifolds as it makes for a very complex casting and more complex is more risk for casting defects that may take some time to present themselves as is probably the case here.
There may be some other finer detail issues to consider fitting the later 6 port engine and I'm sure others will chime in on this but from a mechanics hourly rate and hours required perspective a replacement engine is probably a better option.
Phil

Thanks for the advice. Sounds like I got a lemon that someone else didn’t want to fix. I’m curious now how much it would be to convert to a 6 port head and turbo. I’ve read some threads on that, and most are doing the swap for slight power gains above 1000hp. I originally had aspirations to build this thing out, but all my money is going to making it run right. Ouch… Again I appreciate the honest feedback ?

 

[Ozzymosis]

I admit this looks suspicious to me, too, but you could get a conclusive answer with one of those NOx detector tool things. It will change colors if combustion product is in your coolant mix.

I believe the Mechanic that diagnosed the crack ran all those tests with no results which seems odd to me, but he’s more qualified to diagnose the issue then I am.

 

[Ozzymosis]

I’ll give you 20k for the car problems and all. Just kidding. I’d send it to a reputable shop, if you don’t know where to start diagnosing. Pm me if you want suggestions.

Lol make it 35k and you got a deal!

 

[lucky phil]

Thanks for the advice. Sounds like I got a lemon that someone else didn’t want to fix. I’m curious now how much it would be to convert to a 6 port head and turbo. I’ve read some threads on that, and most are doing the swap for slight power gains above 1000hp. I originally had aspirations to build this thing out, but all my money is going to making it run right. Ouch… Again I appreciate the honest feedback ?

Not sure of head availability but knowing mechanics these days and how hopeless the majority are they will likely charge you a massive labour rate/hours and still cock it up. So maybe a good SH engine is a better option. Even the dullard mechanics these days can generally do an engine swap.
Phil

 

[Ozzymosis]

Forgot that I had this photo as well that shows coolant residue on the turbo. I figure I’d throw it on here incase it can help someone else figure out what’s happening with their’s.

 

[Danimal]

Hmm, yeah that’s interesting. I’ve no experience with this type of issue, a coolant leak in the exhaust path on a gasoline engine, but I’m guessing most don’t making this harder to diagnose. Those casting issues do seem suspicious - though it’s so hard to tell from boroscope images. I’m thinking you could also pressurize the cooling system and watch those spots with the boroscope but I can also imagine that heat may play a role - i.e. when the engine is running.

 

[JOutterbridge]

Hmm, yeah that’s interesting. I’ve no experience with this type of issue, a coolant leak in the exhaust path on a gasoline engine, but I’m guessing most don’t making this harder to diagnose. Those casting issues do seem suspicious - though it’s so hard to tell from boroscope images. I’m thinking you could also pressurize the cooling system and watch those spots with the boroscope but I can also imagine that heat may play a role - i.e. when the engine is running.

Dumb question but since it's in the head can't a pressure test be done on the exhaust side? I think the coolant color test would work to verify it's burning coolant. And an exhaust pressure test back to the head if the leak is really bad. Problem is a hairline crack is normally pretty small until everything is heated to operating temps
No extended warranty?

 

[lucky phil]

Dumb question but since it's in the head can't a pressure test be done on the exhaust side? I think the coolant color test would work to verify it's burning coolant. And an exhaust pressure test back to the head if the leak is really bad. Problem is a hairline crack is normally pretty small until everything is heated to operating temps
No extended warranty?

Can you think of a way to get all the exhaust valves in the closed position at the same time?
Phil

 

[JOutterbridge]

Can you think of a way to get all the exhaust valves in the closed position at the same time?
Phil

I can't:/ Seems way too difficult and time consuming in reality. I was thinking of pressurizing the intake to the exhaust side with the exhaust manifold plated off. I guess that would pressurize the crankcase though even if all valve positions are known

 

[taco_t1a]

Have you talked to graveyard performance? What shop are you taking it to?

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