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The mkiv Supra Owners Club

Explain the front crank seal problem for me


Hank_Swe

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Since i've noticed that my Supra have started to leak oil (it sometime leave's traces, both small and more excessive) im pretty sure my front crank seal is starting to give up.

 

After reading about it on various threads im happy that nothing major has happend...yet. I need to sort this out. But explain why this problem can cause so much damage to the engine?

 

I've read that the seal eventually will break completely. What happens next? The engine is drained out of oil pretty instantly. Problem noticed. But if you're fast of notice, and pull over and stop the car, will any other damage occur?

 

I've also read that replacing the seal is a royal pain in the ***. If im not up for the task, what's a reasonable fee if i should let a shop do it?

 

And pardon my bad english ;)

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If you do a search for anything front main seal related, you will find a lot, and most will tell you that 98% of the time a worn oil pump is responsible for the front crank seal leaking, so its best to replace the pump also, not an easy job as its either engine out, or drop the front sub- frame in order to remove the sump, which is necessary to remove the oil pump.

 

As for catching it and shutting the engine off before it dumps all the oil..........well its a case of luck, if the seal is alread weeping then you can take a chance and just change it, and hope it doesn't let go big time, or change the pump at the same time and relax,

Sometimes the seal can just leak at a noticeableble rate and if your lucky you will see the low oil light come on and be able to stop before the sump is empty (this happened to me) and once i had changed the pump and seal i fitted ultra bright LED in tandem with the low oil light just in case!

 

But the worst scenario would be the seal failing at high RPM and the sump emptying in a matter of seconds, the result would be complete engine seizure.

Edited by Tricky-Ricky (see edit history)
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I need to replace the seal and oil pump. What's the use of having a sports car with lots of power if you can trust it to perform safely. But the work of replacing it... I'll probably let someone else do it. I tought this could be handled within a weekend.

 

I'll let the local Toyota workshop do it.

 

Anyway...thanks for your help! =)

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Dont forget some of these cars are 19 years old!

 

I advise to pull the engine. I did it by dropping the subframe, and half way through, wished I had just taken the engine out.

As Ricky said, you may be lucky, and catch it before all the oil ends up on the underside of the car, but its advisable to get it sorted before going anywhere really.

 

Once the engine is out, its pretty straight forward I found. IIRC lower and upper sump off. Front covers on the engine off. Oil pump has 4 or 5 bolts in it. Take these out. Remove pump. Put new FMS in the new oil pump (make sure the seal is LEVEL in the pump, as pushing it too far can cause problems) put new oil pump in, covers back on. Sumps back on, new oil and filter, engine back in, sorted :)

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How long did it take you to do Listy ? Would you say thats it not a hard job for competent person ?

 

Does anyone know how many hours labour your looking at for a garage to do it ?

 

IIRC I think I was quoted £600 for fitting which also included the cost of new pump / front seal

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A couple of further questions regarding this matter.

 

1. Does replacing the gasket require lifting the engine?

 

2. Im all for a good service, but there must be some way of finding out if the oil pump has caused the problem before the decision is made to raise the engine? For eg, reading the oil pressure? If my pressure is fine, why replace the oil pump? I've had V8s (LS1, LT1) Volvo T5s running 20 psi of boost. Never ever have i needed to replace the oil pump.

 

3. I've read on another forum that an improved seal has been produced and distributed by BECK/ARNLEY. This one will last longer according to the thread. Should i opt for one of these instead of Toyota OEM?

http://www.mkiv.com/tmp/front_crank_main_seal_new/

 

4.As i think of it, my problems began during my oil change. Since we dont get Mobil in the right viscosity i had to go for the Castrol. Could this have had an impact on the leaking?

 

5. Since a lot of Supras sleep during the winter, is it possible for the seal to dry out since the engine isn't driven for several months? Should i start her up every now and then?

 

 

A lot of questions, but your help is very valuable since Supras are a bit more rare in Sweden which also affect the level of know-how regarding these cars over here ;)

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1. No

 

2. The only way to see if the oil pump is worn is to remove it, so yes, toy would need to pull the engine. Oil pressure is no guarantee its fine. A worn pump will hold pressure, but can go at any time. My oil pressure was fine until the moment it went.

 

3. Toyota OEM is fine.Mine lasted 19 years!

 

4. I use Castrol 10w 40 magnatec (iirc) Never had a problem with it.

 

5. It shouldnt dry out, but it is always advisable to run the engine every now and then, to make sure everything has a good coat of oil.

 

Hope that helps.

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Thanks for the advice Listy. So to sum up, i could try fitting a new seal initially. If this also starts to leak, then it's final, i need a new oil pump as well? I just dont want to do a massive amount of work if it's not neccesary. My car "only" has 120 000 km on it with a full service history. But i guess milage isn't everything when the car gets to be 16 years old.

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The only reason its advised to replace the pump is a blown FMS is commonly caused by a worn oil pump. Most prefer to just dig in and change it, to be on the safe side.

 

You could try fitting a new seal first, but if the pump is knackered, you may not be as lucky second time around when the seal goes again, and all your oil could end up on the floor before you get a chance to stop, cue the engine running dry and much more damage being caused.

 

I strongly recommend changing the pump, just for the piece of mind knowing its good.

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The "uprated" seal the the US guys use is just a band aid, most of them are still convinced that front

crank seal failure is due to crankcase over pressure, tried to convince them that that wasn't the case, but they are to full of themselves to listen, despite posting the results of my crankcase pressure tests at various RPMs and boost pressure's with a mix of hybrid and big single turbos.

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Update..im going to drive my car the 45 miles to the Supra-mechanic this sunday. I got a god deal on replacement of the seal, cam belt and oil pump, oil change. Guess my BPU-dreams will have to wait another year. But at least i'll know the car is safe to drive when in comes to oil pressure. And despite of everything..i still love my Supra a lot ;P

 

Thanks for all your help! If anyone needs assistance on the LT1/LS1 engines...im your guy ;) Im also a certified public auditor, so if your having issues with your taxes, i'll give you a hand ;)

 

Cheers!

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