Supra Forums banner
1 - 20 of 34 Posts

·
Registered
87 Turbo, 7M-GTE & R154
Joined
·
14 Posts
Discussion Starter · #1 ·
I've been restoring an 87 Turbo as a project. This is the first Supra I've owned. I was taking it for a routine test drive after fixing the speedometer, clutch, and some other minor stuff. I was checking the temp gauge consistently for the first bit of the drive, but it was obscured by the wheel for the second half. Its never had a cooling issue before so it slipped my mind. When I rolled back into my driveway, a little bit of steam came out from under my hood. I immediately shut it off. It was in the red when I checked. Based on a photo my gf took while driving, it was in the red for probably 3 or 4 minutes. I realize I f'ed up big time.

Engine still cranks and starts fine. Engine has 119k on it, single owner before me. I was planning on rebuilding it soon anyways, my main concern is the block. What are the chances it is salvageable? I'm gonna pull it after I get home from school, but should I be planning on a swap or a rebuild?

Also, does anyone know a good place to get a 7M block?

Thanks everyone.
TLDR; 7M overheated in the red for 3-4 minutes, do you think the block is salvageable?
 

·
Registered
Joined
·
923 Posts
I wouldn't give up on it by any means at all. Fill the cooling system (correctly by the way - heater on, etc), restart and get it up to temp in the driveway with the hood up and looking over and under it for a leak, then drive it around close to home watching all guages, stop back home and idle it with the hood open to confirm you're not spewing coolant, etc. If it passes these tests take it for a longer drive with the same careful awareness.

If it passes this test, drive it for a few days with the same careful awareness.

Don't make a decision to "pull it" with just one event in your database. This is not an exotic, high strung engine operating constantly on the limit of its physical abilities, so don't give up.

Once you've done each step, post back with your findings. Also, where are you in the event one of us lives nearby. Welcome to the madness.
 

·
Registered
Joined
·
22 Posts
Overheated blocks beyond return usually result in a cracked block. If misfiring:
1) replace spark plug
2) replace wires
3) Have a beer and give yourself a pat-in-the-back
 

·
Registered
Joined
·
923 Posts
Hmm, I don't want to start an argument some might consider pointless, but I've never, ever seen a sparkplug damaged by an overheat unless the cylinder was so hot the aluminum pistons were spitting melted bits off and physically hit the plug. The spark plugs can take a lot more heat than the rest of the cylinder components. So, don't replace a single thing here. I didn't hear anything about a misfire - just starts and runs normally. Refill it. Start it. See what you've got.
 

·
Registered
89 Turbo - 2JZGE-T VVti (build/swap in progress)
Joined
·
253 Posts
I'd follow Doug's advice, as well as look for bhg signs. 7M's like to do that
 

·
Registered
87 Turbo, 7M-GTE & R154
Joined
·
14 Posts
Discussion Starter · #8 ·
Thanks everyone for all the replies. I don't think I heated the block to the point of no return, per say. It still starts and runs smoothly; no misfiring. I would have thought the head gasket but the oil is perfect. I'm going to check the thermostat tomorrow. I'm flushing the old coolant and changing to Toyota red, so I figured it would be a good time.

The reason I am so concerned is because I was planning on pushing the 7m to ~450hp later down the line. I don't want to tear it down for a rebuild later on just to find out the block is busted, you know?

I live in the Richmond VA area, but I'm headed back to college in a few weeks and I'm leaving the supra behind.

Really though, thank you guys for all the help. I've been wrenching on cars for years now but I'm still learning.
 

·
Registered
87 Turbo, 7M-GTE & R154
Joined
·
14 Posts
Discussion Starter · #9 ·
Some more info about the incident:
As I pulled into the drive way the steam was coming from a small stream of coolant coming out of the overflow tank. Even though I turned off the engine coolant kept coming out of the tank, faster than before actually.

I've never had overheating issues, but I mostly drove the thing before the summer heat came. I also had recently remove a circuit the previous owner had wired up to keep the fans running after the engine was shut off (part of a bigger battery drain issue I'm working on), however the fans still run while the engine is on.
 

·
Registered
89 Turbo - 2JZGE-T VVti (build/swap in progress)
Joined
·
253 Posts
Some more info about the incident:
As I pulled into the drive way the steam was coming from a small stream of coolant coming out of the overflow tank. Even though I turned off the engine coolant kept coming out of the tank, faster than before actually.

I've never had overheating issues, but I mostly drove the thing before the summer heat came. I also had recently remove a circuit the previous owner had wired up to keep the fans running after the engine was shut off (part of a bigger battery drain issue I'm working on), however the fans still run while the engine is on.
Maybe hit it with one of those hydrocarbon testers that checks for exhaust gas in the coolant? If a bhg is between the cylinder and the coolant jacket, the oil will be fine. But the coolant system will get pressurized and blow coolant out of the overflow tank. Are you running oem hg/bolts?
 

·
Registered
Joined
·
34 Posts
I think you are fine based on my personal experience.....

I was out with my parents for a fun long weekend of driving in the mountains in Germany followed by a few days in Adenau at the Nurburgring. ( I live in europe) my 7mge started running hot already on the autobahn on the way there. But hey it was a very hot day and it wasnt tooooo bad. So we pressed on and arrived at our hotel in the evening.

I ran the thing all week, got it to boil several times and even drove the 300 miles back to my house at 100mph constant speed on the autobahn. I couldnt do anything because I didnt have parts or tools with me, so I just ran it during the whole week and even did a boiling lap of the ring with it. Just filled her up everytime and made sure the air was out of the cooling system everytime I filled her up.

When I got home I pulled the head and my suspicion of a blown headgasket was confirmed, Rebuild and machined the entire head, put in a new fresh headgasket and all is good! The block was perfect even after boiling it daily for a week and on the way home for a prolonged amount of time. So I really think you'll be fine after gently driving it for only a few minutes....
263234
 

·
Registered
Joined
·
6,808 Posts
@freemang20
The first question i have,

When you noticed it was overheating, did you let it be OR
Did you attempt to fill it with water?

If you attempted to fill with water, that is usually when the thermal shock happens and you can HEAR it. It will crack on the intake water jackets. If you did not add water, then more than likely your block is ok. :)

Now with that said, that is just the block, i did not mention the head gasket at all. That is a separate issue ;)
 
  • Like
Reactions: freemang20

·
Registered
87 Turbo, 7M-GTE & R154
Joined
·
14 Posts
Discussion Starter · #13 ·
Maybe hit it with one of those hydrocarbon testers that checks for exhaust gas in the coolant? If a bhg is between the cylinder and the coolant jacket, the oil will be fine. But the coolant system will get pressurized and blow coolant out of the overflow tank. Are you running oem hg/bolts?
I was thinking about using one of those coolant combustion leak testers. I'd think it should have the same result regardless of whether I test the exhaust or coolant. Looks to be stock hg and bolts.
 

·
Registered
87 Turbo, 7M-GTE & R154
Joined
·
14 Posts
Discussion Starter · #14 ·
@freemang20
The first question i have,

When you noticed it was overheating, did you let it be OR
Did you attempt to fill it with water?

If you attempted to fill with water, that is usually when the thermal shock happens and you can HEAR it. It will crack on the intake water jackets. If you did not add water, then more than likely your block is ok. :)

Now with that said, that is just the block, i did not mention the head gasket at all. That is a separate issue ;)
Yeah I didn't add anything, just let it sit. Looks like its time for some arp studs & mhg!
 

·
Registered
Joined
·
923 Posts
"Looks like its time for some arp studs & mhg!"

From your above comment above that you can see that it has a stock head gasket and bolts, it sounds like you have already opened it up and are well on your way? Post up some pics - always great to see another Supra and the photos of the work may inspire others to work on theirs.
 

·
Registered
87 Turbo, 7M-GTE & R154
Joined
·
14 Posts
Discussion Starter · #16 ·
"Looks like its time for some arp studs & mhg!"

From your above comment above that you can see that it has a stock head gasket and bolts, it sounds like you have already opened it up and are well on your way? Post up some pics - always great to see another Supra and the photos of the work may inspire others to work on theirs.
So I had to leave from college but will present pics and update the thread when I return. I also have a rats nest of bad wiring to deal with, the last guy hooked up a really cheepo af guage and boost guage along with a stereo straight to the battery. Also wondering if there is anything I need to do about the aftermarket hoost guage? Like what should I do with the leftover vacuum line. I have no idea where its coming from but im fairly sure its independent of the srock guage.
 

·
Registered
Joined
·
923 Posts
Yeah I kinda thought you were guessing there. Anyhoo, refer to my post #4. I doubt you have a problem and that's the way to find out versus running around with your hair afire and tearing down the engine instead of studying.
 

·
Registered
Joined
·
1,721 Posts
Also, does anyone know a good place to get a 7M block?
Worst case scenario, 2005. Those things were plentiful back then. :)

Realistically speaking though, it's a solid deck, iron block engine. As others have pointed out, the head is more of a concern. It can be repaired if not level, at a machine shop, but the hardness of the head may be an issue if it got too hot.

As Doug points out, data is your friend here. Throwing parts at a problem without knowing what the problem actually is can be a great way to lighten one's wallet. In the case of the 1984 6M P-Type Mk2 I picked up in 2008, I had overheating issues. Started with replacing the cheap stuff, working on it and replacing parts that got progressively more expensive. Unfortunately in my case, it turned out to be a bad radiator. On the plus side, by the time the testing reflected that (because it was the only cooling system piece left) I had a fully new cooling system that gave me years of trouble free performance.
 
1 - 20 of 34 Posts
Top