: A spike in coolant temp '93 North*



Mountie
11-25-08, 01:02 PM
Let's say you took an STS for a drive. Went to a couple stores, drove on the freeway for 15 minutes. Everything fine. Coolant temps from 196 to 113. Maybe a 117 for a moment. But the temp lowers back to what you would expect.

Then, you take a freeway exit, go down a couple blocks & make a right turn. You hit the gas for a little moment & rev it to 4,800 for a block, and then slow to make a turn.

Now, the temp went to 224. You drive slowly to make another slow turn and the temp is now 234. You drive up the street 300 yards and now the temp is 245.

You stop at your destination, and the read=out says " Engine Hot". 250!! ( No coolant escaping anywhere - no overflow,etc.)

I shut off the engine. 15 minutes later I start the engine & it is at about 207, and dropping to 198.

I used an Infrared temp gun & the sides of the heads are 198. The Water pump is 198. The hose is 198.

A half hour later I drove home with the temps perfect!! I just did not hit the gas hard.....

Any guess?? A bad Temp sensor? A 2 year old OEM waterpump bad?

The air-bleed pipe seemed clear a week ago.

I'm avoiding the "HG" word at all costs......

( Ranger can suggest it - He worries about a temp spike on a hard excelleration - I can't afford to hear it) :bigroll:

Ranger
11-25-08, 02:54 PM
I shut off the engine. 15 minutes later I start the engine & it is at about 207, and dropping to 198.

I would not put much stock in this as it has had 15 min. to cool down.

I suppose a stuck thermostat is a possibility or a belt tensioner, but the sequence of events is worrisome. Take it out and see if it happens again. Push it hard and try to make it happen. If it does, do a coolant test.

ted tcb
11-25-08, 04:56 PM
See, Ranger replaced the word "HG" with "worrisome".

If you don't want to pay for a combustion kit, they simply drop by a rad shop and they'll do the
test for a nominal sum. Makes sense to get a definitive answer before you start nickle and diming yourself.

Mountie
11-25-08, 05:40 PM
See, Ranger replaced the word "HG" with "worrisome".

If you don't want to pay for a combustion kit, they simply drop by a rad shop and they'll do the
test for a nominal sum. Makes sense to get a definitive answer before you start nickle and diming yourself.

Yea... Ranger is being REAL nice.....:)

I will check the waterpump belt tensioner.

I'll do the test after my week Thanksgiving trip to N. California. As far as I'm concerned, I re-did so much when I swapped Northstars myself, Tranny new, & re-did everything around the engine, ...Heck, just getting a long block from the De-funcked - Bankruped G.M., and throwing it in may be worth it to me. ( How much $$$$$ for a newer performance car nowa-days?)

A long block is less than $4K? Verses a sert-job, etc., R&R?

I wonder what $$ I could get for this hunk of metal, ONLY needing a block?

ted tcb
11-25-08, 06:18 PM
Definitely a car worth putting money into.
I've never seen an STS with those rims ... your car is a stunning modern classic.

Normally, I'd say don't jump to conclusions, and cross everything off your list before considering HG's.
But 250f on a 16 yr old N* is not a good sign, and random temp spikes are typical when they start to go.

Go further down in this forum section, and you'll see where 97Eldo has tightened down the heads on over 40 N* motors,
with no failures to date. He puts metal studs in the block, and tightens the head down with great results for about $1200USD.

If you have a problem, you should contact him.
California is a long way from London, On., but you're car is so nice, I'd hold onto it.
An old STS with an overheating issue is pretty much only worth whatever you can sell the tires/rims for.

Mountie
11-25-08, 06:45 PM
Definitely a car worth putting money into.
I've never seen an STS with those rims ... your car is a stunning modern classic.

Normally, I'd say don't jump to conclusions, and cross everything off your list before considering HG's.
But 250f on a 16 yr old N* is not a good sign, and random temp spikes are typical when they start to go.

Go further down in this forum section, and you'll see where 97Eldo has tightened down the heads on over 40 N* motors,
with no failures to date. He puts metal studs in the block, and tightens the head down with great results for about $1200USD.

If you have a problem, you should contact him.
California is a long way from London, On., but you're car is so nice, I'd hold onto it.
An old STS with an overheating issue is pretty much only worth whatever you can sell the tires/rims for.

The rims are made buy the company that does Upgrades for BMW & Mercedes ( 18" & 245/45 tires )

I swapped North*'s by raising it up & out. I am not afraid of a hassle.... If I can do studs without actually pulling the engine, I could do it in my garage at home.

Maybe just drive it without jumping on the gas peddle.
I remember, when my GMC truck had bad valve guides fouling plugs, I asked a race mechanic about doing a head job. He said, " What's cheaper? Putting spark plugs in it every other month? Or $1,500 for heads??".

I ended getting a new 350 Chevy long block engine for $1,400 at his cost eventually.

But the point was, this STS is my weekend car. No fog report out the back yet.....

But really, if I have to pull the engine, I'm getting a new G.M. long block. At lease it will cure the oil dripping on the ground.:hmm:

We'll see after Dec. 4th.

Ranger
11-25-08, 10:11 PM
Even IF you could get the heads off and the studs in with the engine in the car, you'd never get the heads over the studs to drop them in place.

Mountie
11-26-08, 12:18 AM
Even IF you could get the heads off and the studs in with the engine in the car, you'd never get the heads over the studs to drop them in place.

Frigg'n General Motors......

If I had to drop the whole drivetrain assy below, with help. about how long does it usually take?

After this evening I'll be wine tasting in Napa / Sonoma County, Ca. tomorrow evening.

That'll help.......:alchi:

I'll tell Coppola you guys said 'Hi'...

Ranger
11-26-08, 11:46 AM
Having never done it I could not give you an estimate. I guess it depends on you experience, how well you're equipped and how much time you have to devote to the job, but I would guess several days at very least. Probably more like several weeks if you're doing it in your spare time.