Cylinder Bore

GBS 90 SC

Registered User
I just had a local machine shop rebuild my engine and it runs too hot going down the highway. Seems to be OK in town and at lower RPMS. All the cooling system components have been replaced and it still can not recover after going down the highway.
Can anyone tell me if it is OK to bore the cylinders on our blocks? If so, how much over can we go and still be safe?
I need to see if I can find something published from a tech manual or something of that nature.
(The shop I used went 0.030" over.)
 
I went .020 over, If you go over .030 it might be a good idea to have the block ultrasonic tested.
Why did you go .030? What pistons did you use?
Check and make sure your fan is working correctaly.
Did you put a new radiator on the car?
 
The radiator is new(Valeo, OEM) and I probably should have gone after-market there. I really don't know why the shop had to go 0.030" over. The car had blown HG's and 134K miles, so I went ahead with a complete rebuild. It appears that 0.030" is too just too much.
I wonder if this has happened to anybody else?
What are my options?
 
.030" is pretty standard and shouldn't be any problems whatsoever.

I'd look for other things like stuck t-stat, bad fan, missing air dam or air stuck in the system (you opened the vent right?). My car ran at 235 on the highway when the airdam was ripped off. Was under 200 any other time. Made an airdam out of aluminum and it's fine now.
 
Yeah I agree .030 over would not make the engine run hotter. You have something else going on. With a new radiator that rules the rad out. Could be the thermostat. I've put new ones in that were faulty.
 
If it's just running hot and not really overheating, that might be partly normal. New engines run hotter because of all the tight tolerances, until everything gets broken in after a few thousand miles. If it's really excessive maybe something else is going on. You definitely need to purge the air from the system several times to really get it all out.
 
Purging air from cooling system

Would this be just a matter of loosening the the vent plug a few times after driving?
 
I usually open the vent plug before starting the car, put a towel around to catch any drips, then start the car. Close it as soon as coolant starts coming out (which will be very soon after starting it).
 
NO do not do that after the car is hot you will get a shower of scalding hot water and antifreeze burns take awhile to heal. I personaly know this.

Elevate the front of the car alittle by parking on an incline or using ramps. When the engine is cool remove the vent plug and refill the radiator until coolant comes out, if air bubbles are coming out give them alittle time to work out and keep refilling the rad until there are no more bubbles coming out then reinstall the vent plug. Now fill the overflow bottle and start the car up and let it idle till it gets up to oporating temp. Now shut the car down and let it cool, keep an eye on the overflow bottle because as the coolant cools it will pull water from the bottle back into the cooling system. Make sure you do not let the overflow bottle run dry or you will pull air back into the cooling system.
Drive the car paying attention to the temp, dont let it overheat and keep the overflow up to level. Eventually you will work all the air out of the system and the coolant level will stabilize.
Some cars I've had to this with for a couple of days to get all the air out.
 
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