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1989 Stock 7MGTE, R154
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Discussion Starter · #1 ·
Hi guys, been a while since I've posted here, but I was wondering what my next steps with my 1989 7mgte. Found out today I likely have washed out bearing as fuel had gotten in the oil as well as a possible failing piston wrist pin and was wondering what I should do. The car still needs a decent amount of work, paint and quite a few things, and I mainly wanted to hear your opinions on it. Should I rebuild it, or should I sell it and buy another one? I'm leaning towards the rebuild side, but I understand I'll need to get the car painted, and that won't be cheap either. I am not mechanically inclined or confidant enough to do a rebuild on my own; I would be sourcing it to a shop. Thanks!
 

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87 supra on silvers neo max
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personally, if you have the time, patience, and money, I would rebuild or even swap out the motor. 7m's are cool but not worth rebuilding twice. If your chassis is clean and has zero rust (surface rust is fine, especially in easy to reach areas like spare wheel well) then it's definitely worth saving the car for yourself and have some sort of rebuild plan for it.

At the end of the day, it's really up to you. I'm young, so I'm pretty familiar with the gen z crowd. a70 supras are starting to be popular with younger audiences esp with all the 80/90s grunge emo craze going on lol. if you want that kind of clout go for it. if it's too much of a hassle and you rlly just wanna get along your day, then its safe to let it go too. dont feel pressured to keep an 80s shit box tho.

Also share some pics if you dont mind
 

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1989 Stock 7MGTE, R154
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Discussion Starter · #3 ·
Thanks for the response. I am only 20 myself, and generally I hate the gen z crowd, at least with some things in culture as well as in cars (I think stance is VERY stupid and pointless and doesn't even look good). The chassis is straight, and the only rust I can think of that is really bad is the battery tray, its completely gone. My intent with the car is to take it on a roadtrip, so the rebuild would be within OE spec, also because I really enjoy the drivability of the stock 7mgte. This is my first ever time having an engine that needs a rebuild, which is the main reason I ask, and I have no idea where to get the motor rebuilt at. The shop I brought it into had called almost all of their engine rebuilders and they said they don't rebuild that engine (or something along those lines). I'll send some pictures once I get around to it. Thanks again for the advice
 

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so point blank. Long term, the cars that were not swapped are fetching the best money.

ie a MA70 that is turbo with a Turbo money. Not a NA swapped to turbo.

The issue is that the 7M is not known to most shops unless they specialize in supra's. Sound Performance out of Illinios is one of those shops that KNOW the 7M (Larry Prebis).

On to your post.

Are you hearing rod knock? The 7m is not known to washout engine bearings.
Also what leads you to conclude a wrist pin on the piston?

The 7M has a glass jaw and neither of what you describe is it.
 

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87 supra on silvers neo max
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Thanks for the response. I am only 20 myself, and generally I hate the gen z crowd, at least with some things in culture as well as in cars (I think stance is VERY stupid and pointless and doesn't even look good). The chassis is straight, and the only rust I can think of that is really bad is the battery tray...
thats crazy, they couldnt rebuild a 7mgte? my homie rebuild 4 7mgte's within 4 yrs just cuz he was being stupid with the other ones 💀. idk bout stance though. I guess in my area people build stance and air suspension cars tastefully. one of my mk3 friends (same one who rebuilt 4 7mgte) installed air suspension in his car and ever since then, even with poopoo paint, he has been in car shows.

also im 18. turning 19 very soon. installed coilovers and even replaced my aging coolant hoses on the 7mge with hps hoses on my own (im lying I had small help but I did most of the jobs by myself). I already rebuilt my 7mge but it's starting to blow and since it's already been rebuilt once, I'm not gonna bother keeping it. Later this year I'm swapping it out for a 2jz-ge. I might even record it and make a tutorial-like video with it so that the newer mk3 supra owners considering a 2jz swap have some inspiration. sucks that most of the old swap info is gone so Im gonna try my best to contribute to the community and keep these chassis alive. being a film major has its benefits lol. I hope your plans for your car goes well, whether you rebuild it or sell it.

also explain the motor problem more too
 

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1989 Stock 7MGTE, R154
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Discussion Starter · #7 ·
so point blank. Long term, the cars that were not swapped are fetching the best money.

ie a MA70 that is turbo with a Turbo money. Not a NA swapped to turbo.

The issue is that the 7M is not known to most shops unless they specialize in supra's. Sound Performance out of Illinios is one of those shops that KNOW the 7M (Larry Prebis).

On to your post.

Are you hearing rod knock? The 7m is not known to washout engine bearings.
Also what leads you to conclude a wrist pin on the piston?

The 7M has a glass jaw and neither of what you describe is it.
Thanks for the response. The main reason I am leaning towards a wrist pin or some form of rod knock is mainly because of the way it sounds. It almost sounds like piston slap, and the sound is mid or lower within the engine. I know the car in the past had blown head gaskets but I am unsure if the rod bearings were ever done as well (along with the head gasket). You hear it right when you start it cold, and when its running you'll hear it if you get on throttle a little bit (2k-3k RPM is generally where the noise kicks in). The main reason the washout was important was mainly because the oil was fresh, and was much thinner than it was prior, and smelled of fuel or something along those lines. Sorry if I am a little ignorant, I've been trying to learn all of this stuff but it takes time. The car itself is a factory 5speed 7mgte, or a MA70 turbo.
 

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esp with all the 80/90s grunge emo craze going on lol
geez that stuff is coming back? well i guess there's another generation that can recount the cringey and awkward memories in their goth/emo phase lol
even replaced my aging coolant hoses on the 7mge with hps hoses
Beware of silicone coolant hoses; water/coolant permeates through silicone 15 times faster than regular EPDM rubber hoses. You will need to check your coolant often and make sure it is topped up. I've posted this a few times on this forum but I'll say it as many times as I need to. It's like electric radiator fans; unless you are aware about their shortcomings, don't fall for the silicone hose meme.
 

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87 supra on silvers neo max
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geez that stuff is coming back? well i guess there's another generation that can recount the cringey and awkward memories in their goth/emo phase lol
...
kinda? It's more of a mix of everything since everyone thrifts vintage stuff. a mix of y2k but monochrome outfits with lengthy 90s haircuts. also mullets. a lot of mullets. korean style mullets mostly, without harsh fades. not the american mullets people wore in the 70s or something.

Beware of silicone coolant hoses; water/coolant permeates through silicone 15 times faster than regular EPDM rubber hoses. You will need to check your coolant often and make sure it is topped up. I've posted this a few times on this forum but I'll say it as many times as I need to. It's like electric radiator fans; unless you are aware about their shortcomings, don't fall for the silicone hose meme.
wow I actually did not know that, I thought silicone hoses are simply just more expensive rubber hoses with increased durability. when you say permeate, do you mean in like a scientific way? Like the water WILL actually pass through the microscopic pores of silicone???? thats crazy. I learned that in my high school college level biology class
 

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Heh, I guess it makes sense, fashion trends tend to look back 20-30 years from the present time. 2010s through to now it was 90s-00s stuff. In the 80s it was the 50s-60s.

And yes, the water will actually pass through the pores in silicone over time. Much, much faster than EPDM rubber. They sure do look nice, but they're not worth it if you're not the kind of person to check things over in the engine bay frequently, and consistently. And I know I myself definitely don't do that.
In fact that's one of the things I like about the 7M - it's old, but once the head gasket is fixed, it is a very reliable engine that also lets you have some fun too, because I've lost count of the times I've gone out and done some hard driving down some back roads, on a whim, and not once has the engine complained in any way about it.
Something you can do, buy some UV dye that's ok to use in vehicle cooling systems and add some to yours, then after a month or so, shine a UV light on the engine bay and watch the hoses light up.
 

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Hi guys, been a while since I've posted here, but I was wondering what my next steps with my 1989 7mgte. Found out today I likely have washed out bearing as fuel had gotten in the oil as well as a possible failing piston wrist pin and was wondering what I should do. The car still needs a decent amount of work, paint and quite a few things, and I mainly wanted to hear your opinions on it. Should I rebuild it, or should I sell it and buy another one? I'm leaning towards the rebuild side, but I understand I'll need to get the car painted, and that won't be cheap either. I am not mechanically inclined or confidant enough to do a rebuild on my own; I would be sourcing it to a shop. Thanks!
More likely that coolant mixed with the oil or it's just a tired old 7M with worn bearings. Not unusual since they youngest of these engines is ~30 years old and many of them have lived a hard life of sports-car redlines and use.

Possible failing wristpin? That would be VERY unusual for a 7M. Not impossible. But if you're hearing a light knock and it seems like it's toward the top end of the engine, if it's RPM dependent and gets worse as the engine heats up - I have bad news, it's almost certainly rod knock and not a wristpin.

Personally I would start by buying the tools you need to work on cars like this - cheap box end wrenches, sockets, ratchets, etc at Harbor Freight works just fine. Get full metric sets that include 8, 10, 12, 14, 17, and 19mm sizes. Gearwrench or similar ratcheting box ends are amazing and worth the money -get the same sizes. Harbor freight also has 'extended' box end wrenches that are longer than normal wrenches, get those in the same sizes plus 21 and 22. Get a screwdriver set as well.
Add an aluminum 3+ton floor jack, jackstands, some drip pans and misc funnels, along with a no-drip coolant funnel. All in all you can get this done for $500-700, and that'll be all the tools you need to do 80%+ of any work you'll need to do on a MK3. Don't forget gloves and safety glasses!

If you have all that already, awesome, but start researching on how to pull the engine and transmission. You'll need to rent, borrow, or buy an engine hoist for that. If you have the ability to store an engine hoist, I'd strongly consider spending the $300ish on one from Harbor Freight. Get a 2-ton model because it has a much longer arm that reaches into the MK3 bay at a 1/2ton position WAY better than 1 ton models. Get the load leveler as well.

Pulling the engine will be the most labor intensive (aka pricey) part of an engine rebuild so as long as you can pull the engine yourself and get it to a machine shop on your own, you'll be saving a ton of money even if you have them do the whole rebuild.

I noticed you called around and didn't find a lot of shops willing to do that - did you ask them about the whole job as in you bring them a car and they rebuild the engine? Or did you ask them about bringing them an engine and them rebuilding the bottom end and cyl head for you, and you pick up just those components as completed items?

Either way, your choice now is to sell the car as-is for a nut-kick price since the engine's toast, or pull the engine and properly diagnose the exact failure. If the failure is repairable and easily rebuilt - rebuild it! If not, you know it's time for a fresh engine or an engine swap from elsewhere.

I hope that helps.

geez that stuff is coming back? well i guess there's another generation that can recount the cringey and awkward memories in their goth/emo phase lol

Beware of silicone coolant hoses; water/coolant permeates through silicone 15 times faster than regular EPDM rubber hoses. You will need to check your coolant often and make sure it is topped up. I've posted this a few times on this forum but I'll say it as many times as I need to. It's like electric radiator fans; unless you are aware about their shortcomings, don't fall for the silicone hose meme.
The permeation rate is still on a geological time scale relative to the maintenance these cars need already. I've had silicone hoses in several cars, one since ~2008, and I've never had unexplained coolant loss or low coolant because of it. The explainable coolant loss in that car was from failing old rubber hoses. :)

So, yes, there's some material science properties to consider and it's worth bringing up. But the realities of these cars tend to render that difference insignificant, though.
 
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I stand corrected then. Gates did have a pamphlet on it if anyone wants to do some extra reading, however this pamphlet has been around for quite a while. Things might have changed in the years since and silicone hoses might actually be on par with, if not better than rubber hoses now.
 

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Oil and silicone I know for sure, but I'm definitely talking about coolant, from that pamphlet I linked to before:
Slope Font Parallel Rectangle Number

Note that this paper has to be at least 10 years old however. A lot of things may have changed since. I wonder if hoses exist that have an EPDM inner layer with a silicone outer layer.
Also, it mentions trucks that are driving with a "two shift per day" driving cycle. I dunno how long a shift is, but I imagine it's a good part of the day, and truck engines definitely have far more operating hours than most car engines in a year.
 

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Oil and silicone I know for sure, but I'm definitely talking about coolant, from that pamphlet I linked to before:
View attachment 284703
Note that this paper has to be at least 10 years old however. A lot of things may have changed since. I wonder if hoses exist that have an EPDM inner layer with a silicone outer layer.
Also, it mentions trucks that are driving with a "two shift per day" driving cycle. I dunno how long a shift is, but I imagine it's a good part of the day, and truck engines definitely have far more operating hours than most car engines in a year.
Great data! But the takeaway is in the details here.


The test case from Gates has a Class 8 truck - a 53ft semi truck - on a two-shifts-per-day driving cycle (16 hours per day) so let's assume they're talking 5 day work weeks. 52 weeks a year.
So 52 weeks x 5 days per week, 260 days.
260 days x 16 hours/day per driving, we have 4,160 hours (A LOT!) of operation. Being a semi we'll make a semi-wild-ass-guesstimate average speed of 30mph between highway, surface streets, and idling. Which puts us at 124,800 miles of operation.
According to that graph, at a nominal 88* C coolant temp we're losing >1L of coolant via permeation through the rubber hoses, or losing 15L of coolant through silicone hoses over that period of time.

So if I was a fleet manager of a trucking company, or a logistics dweeb for the Army advising TACOM on what to choose for heavy tactical vehicles, the easy answer would be rubber hoses. Because the thermal resistance and added durability of silicone doesn't outweigh the benefits over the long haul of far less coolant use and less cost per hose of the rubber hoses.

...But if I was choosing a hose for a high performance application that absolutely could benefit from the added heat resistance, thermal stability, etc - and my usage schedule was far, far lower to the point where the additional coolant loss was insignificant; I'd choose the silicone hoses.
 

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That's exactly why I brought up the caveat about it being a truck engine; they operate for far longer hours than most passenger cars will ever see before getting scrapped.
Boiling down to personal preference, I've never really been a fan of silicone hoses. For whatever reason I just like how regular rubber blends in. Probably related to how when I was a kid I'd get hyped seeing a ferrari or similar, but now I get more excitement seeing an A80 supra with stock wheels.
 

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1989 Stock 7MGTE, R154
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Discussion Starter · #18 ·
More likely that coolant mixed with the oil or it's just a tired old 7M with worn bearings. Not unusual since they youngest of these engines is ~30 years old and many of them have lived a hard life of sports-car redlines and use.

Possible failing wristpin? That would be VERY unusual for a 7M. Not impossible. But if you're hearing a light knock and it seems like it's toward the top end of the engine, if it's RPM dependent and gets worse as the engine heats up - I have bad news, it's almost certainly rod knock and not a wristpin.

Personally I would start by buying the tools you need to work on cars like this - cheap box end wrenches, sockets, ratchets, etc at Harbor Freight works just fine. Get full metric sets that include 8, 10, 12, 14, 17, and 19mm sizes. Gearwrench or similar ratcheting box ends are amazing and worth the money -get the same sizes. Harbor freight also has 'extended' box end wrenches that are longer than normal wrenches, get those in the same sizes plus 21 and 22. Get a screwdriver set as well.
Add an aluminum 3+ton floor jack, jackstands, some drip pans and misc funnels, along with a no-drip coolant funnel. All in all you can get this done for $500-700, and that'll be all the tools you need to do 80%+ of any work you'll need to do on a MK3. Don't forget gloves and safety glasses!

If you have all that already, awesome, but start researching on how to pull the engine and transmission. You'll need to rent, borrow, or buy an engine hoist for that. If you have the ability to store an engine hoist, I'd strongly consider spending the $300ish on one from Harbor Freight. Get a 2-ton model because it has a much longer arm that reaches into the MK3 bay at a 1/2ton position WAY better than 1 ton models. Get the load leveler as well.

Pulling the engine will be the most labor intensive (aka pricey) part of an engine rebuild so as long as you can pull the engine yourself and get it to a machine shop on your own, you'll be saving a ton of money even if you have them do the whole rebuild.

I noticed you called around and didn't find a lot of shops willing to do that - did you ask them about the whole job as in you bring them a car and they rebuild the engine? Or did you ask them about bringing them an engine and them rebuilding the bottom end and cyl head for you, and you pick up just those components as completed items?

Either way, your choice now is to sell the car as-is for a nut-kick price since the engine's toast, or pull the engine and properly diagnose the exact failure. If the failure is repairable and easily rebuilt - rebuild it! If not, you know it's time for a fresh engine or an engine swap from elsewhere.

I hope that helps.



The permeation rate is still on a geological time scale relative to the maintenance these cars need already. I've had silicone hoses in several cars, one since ~2008, and I've never had unexplained coolant loss or low coolant because of it. The explainable coolant loss in that car was from failing old rubber hoses. :)

So, yes, there's some material science properties to consider and it's worth bringing up. But the realities of these cars tend to render that difference insignificant, though.
Hi, thanks for the response. I have decided to keep the car, and found a shop near me that specializes in working on the motors and the MA70 Chassis as a whole, and I will be bringing it there. Unfortunately I do not have the time currently to pull the motor myself, so I will be having the shop do the work. I believe it to be rod knock based on what you guys have said as well as the sound and the fact that I know the car has blown headgaskets in the past. Thank you all for the advice. I asked the shops about an entire rebuild, and this one seems perfectly comfortable doing it and I will be going through with them. Thanks again, I really appreciate it.
 

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Wow - will look forward to some pics! You"ll also need to show us the cam journals when the shop calls to say they're trashed and u need a new head. Nope. They all look like that. Just clean it up and reassemble.... so keep us in the loop while the shop works through things.
 

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Discussion Starter · #20 ·
Wow - will look forward to some pics! You"ll also need to show us the cam journals when the shop calls to say they're trashed and u need a new head. Nope. They all look like that. Just clean it up and reassemble.... so keep us in the loop while the shop works through things.
Alright, I will keep that in mind and keep you guys posted. I am scheduled to bring it in come next Saturday so we will see..
 
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