Engine overheat (1FZ-FE) (4 Viewers)

[josephpampliega]

Incass not already mentiond.

Same symptom happened to mine after all cooling components replaced, turned out problem was overly concentrated coolant mixture. Went through everything and was stumped. Finally decided to check concentration using hydrometer to find out it was a little over 70%.

Once corrected to 50% temps did not exceed 205 deg F at the hottest of temperatures and steepest of grades encountered even at continous extended full throttle.

Read that heat transfer properties of coolant decrease the higher the concentration.

 

[OrangeCrusher]

@josephpampliega Thanks for sharing your experience!

Interesting, I didn't expect this to make such a difference.

Looking at the heat transfer properties of ethylene glycol / water mixtures, it looks like the specific heat of 70% glycol mixture is about 10% lower than that of a standard 50% mixture:

So that makes sense that this will increase the delta T across the radiator and engine block / head, leading to higher peak temperatures.

At the same time however, the boiling point of the coolant increases as well - from about 225F / 107C to 245F / 118C.
(In addition to that, there is the coolant system pressure induced boiling point increase, which is at least 20F above atmospheric even in higher elevations. This effect should be similar for both mixtures)

--> So with going from 50% to 70% glycol, cooling system loses about 10% capacity. However at the same time, the boiling point increases by 20F. This means the system can run 20F hotter before it boils over and really any damage is caused. A 20F hotter coolant system will increase the heat transfer across the radiator at an ambient temperature of say 80F and coolant temp of 220F by about 20F / (220F-80F) = about 15%. So it should about compensate for the lower heat capacity of the coolant.

Altogether, I would expect a system with a higher glycol % to run hotter, but not boil over sooner than one with lower % of glycol in it.

 

[alia176]

The cats have been deleted by PO.

So it also doesn't pass smog test etc. As this is not my daily driver I was able to register it as a vintage vehicle, eliminating the need for smog tests where I live.

I don't really like the fairly strong smell from the exhaust but haven't decided what if anything to do about it. The OE cats are pretty expensive. Aftermarket ones can be found for very good price, but no idea if they are of any use or complete junk.

Aftermarket cats should remove the stinkyness of the exhaust but try to find a "high flow" cat that has less # of honeycomb/sq inch. You're probably throwing a CEL anyway, maybe P0420 which may still continue to happen after the high flow cats go in but at least your spotters won't get teary eyed with your stinkyness . I drove few months w/o cats and the smells were awful when the windows were rolled down during slow crawling.

 

[OrangeCrusher]

Update: The Koyo radiator arrived and I've put everything back together.

Next to the radiator, following things were done:
- new water pump
- flushed out cooling system
- timing retarded 1 degree from 7 to 6 BTDC
- filled with 50:50 glycol/water coolant mixture, same/similar mixture as before

Then I took it to the same section of road as in the initial post. It's maybe 10F cooler today than it was at the time of the earlier post.
All looked good for a while, however at the last mile it again ran very hot >220F. This time I noticed that at the same time:

• I heard it pinging
• power loss, speed dropped by about 15mph - assume the ECU pulled timing, or otherwise power loss due to the pinging

It's very possible the same happened before but I just didn't realize it.

Tank was 1/3 full, so drove it to the next gas station and filled it up with 91 octane premium. Took 14 gallons, the remaining 10gallons were 85 octane.

Then I drove up the same gradient two more times. Both times:

• temperature stayed below 220F, but still elevated
• speed stayed at about 70mph (2nd gear, about 4,500rpm) throughout the entire climb
• I didn't hear any pinging

So my conclusion from this:

1. The main issue here likely was the pinging all along, and I just didn't realize it's happening. She likes premium!
   1. Contributing factor maybe that the snorkel fell off about a month ago and I haven't fixed that yet. Sounds ridiculous, but is true - it was only secured with half the number of bolts that were supposed to be there, and they rattled off on a trail. Now it's probably getting significantly hotter intake air than before.
2. No clear signal so far that the new aluminium radiator is doing any better or different than the old CSF copper / brass. I was very convinced there would be, however looking at them next to each other, there is very little difference. The Koyo aluminium radiator has about 20% more vertical water channels, and the fins between the channels are accordingly shorter. All the other dimensions seemed the same or very similar. Maybe there is still a benefit but from the first drive today I cannot determine it.

 

[LongDuck]

The thread is 4 pages long,... have you checked your fan clutch to be sure it's pulling air when it should? No other changes will matter all that much if the engine cooling fan isn't pulling enough air through the radiator.

 

[alia176]

Update: The Koyo radiator arrived and I've put everything back together.

Next to the radiator, following things were done:
- new water pump
- flushed out cooling system
- timing retarded 1 degree from 7 to 6 BTDC
- filled with 50:50 glycol/water coolant mixture, same/similar mixture as before

Then I took it to the same section of road as in the initial post. It's maybe 10F cooler today than it was at the time of the earlier post.
All looked good for a while, however at the last mile it again ran very hot >220F. This time I noticed that at the same time:

• I heard it pinging
• power loss, speed dropped by about 15mph - assume the ECU pulled timing, or otherwise power loss due to the pinging

It's very possible the same happened before but I just didn't realize it.

Tank was 1/3 full, so drove it to the next gas station and filled it up with 91 octane premium. Took 14 gallons, the remaining 10gallons were 85 octane.

Then I drove up the same gradient two more times. Both times:

• temperature stayed below 220F, but still elevated
• speed stayed at about 70mph (2nd gear, about 4,500rpm) throughout the entire climb
• I didn't hear any pinging

So my conclusion from this:

1. The main issue here likely was the pinging all along, and I just didn't realize it's happening. She likes premium!
   1. Contributing factor maybe that the snorkel fell off about a month ago and I haven't fixed that yet. Sounds ridiculous, but is true - it was only secured with half the number of bolts that were supposed to be there, and they rattled off on a trail. Now it's probably getting significantly hotter intake air than before.
2. No clear signal so far that the new aluminium radiator is doing any better or different than the old CSF copper / brass. I was very convinced there would be, however looking at them next to each other, there is very little difference. The Koyo aluminium radiator has about 20% more vertical water channels, and the fins between the channels are accordingly shorter. All the other dimensions seemed the same or very similar. Maybe there is still a benefit but from the first drive today I cannot determine it.

I applaud your investigation process. . Drive her like you stole her

 

[OrangeCrusher]

Haha! Well, as I said before, I'm trying to be respectful of her age and for any boring long distance drives she can chill on the trailer. But she still needs to stay in shape