- Joined
- Jun 13, 2017
- Messages
- 27
Hey All,
Hate to make another one of these diagnostic threads since we have so many, but I can't seem to find any past posts that really capture my interesting issue. (If there is, a link would be appreciated.)
Anyways, the Cobra runs great, idles fine, sounds amazing. Heat is hot, air is cold, plenty of power and consistent gas mileage. Mostly stock, couple of bolt on's and suspension work, nothing that's given me trouble in the past.
The issue is that when I'm on the highway in 5th gear with revs at or below 2000 the temp gauge starts to climb super slowly. I haven't let it get more than 2/3 of max but based on what I've seen so far it would probably take 30 minutes or more to reach the bad zone. As soon as I notice it, I'll just downshift and it cools itself off.
Now here are my thoughts:
- Seems like some sort of flow issue. When the water pump is spinning faster the temps drop, regardless of speed. Maybe the radiator is restricted? It does have 20 years and 85,000 miles on it.
- OR, maybe it's just getting upset at low speed high load and generating way more waste heat than it should. I don't know what would cause that. Sticky valves maybe?
Here's what I've dismissed so far:
- Maybe there's an air pocket that only impacts at lower coolant flow rates? Nope. Burped the system over 3 days of heat cycling.
- Maybe air is getting in through the reservoir? I don't think so. I replaced the cap with a new motorcraft one and issue is still present. No visual warping or leaking in the reservoir.
- Faulty sensor? Probably not, given that this is a repeatable issue under specific engine conditions.
- Bad thermostat? Well if the stat was stuck it would overheat at all speed/loads, unless maybe it's stuck partly open?
Any thoughts greatly appreciated.
Hate to make another one of these diagnostic threads since we have so many, but I can't seem to find any past posts that really capture my interesting issue. (If there is, a link would be appreciated.)
Anyways, the Cobra runs great, idles fine, sounds amazing. Heat is hot, air is cold, plenty of power and consistent gas mileage. Mostly stock, couple of bolt on's and suspension work, nothing that's given me trouble in the past.
The issue is that when I'm on the highway in 5th gear with revs at or below 2000 the temp gauge starts to climb super slowly. I haven't let it get more than 2/3 of max but based on what I've seen so far it would probably take 30 minutes or more to reach the bad zone. As soon as I notice it, I'll just downshift and it cools itself off.
Now here are my thoughts:
- Seems like some sort of flow issue. When the water pump is spinning faster the temps drop, regardless of speed. Maybe the radiator is restricted? It does have 20 years and 85,000 miles on it.
- OR, maybe it's just getting upset at low speed high load and generating way more waste heat than it should. I don't know what would cause that. Sticky valves maybe?
Here's what I've dismissed so far:
- Maybe there's an air pocket that only impacts at lower coolant flow rates? Nope. Burped the system over 3 days of heat cycling.
- Maybe air is getting in through the reservoir? I don't think so. I replaced the cap with a new motorcraft one and issue is still present. No visual warping or leaking in the reservoir.
- Faulty sensor? Probably not, given that this is a repeatable issue under specific engine conditions.
- Bad thermostat? Well if the stat was stuck it would overheat at all speed/loads, unless maybe it's stuck partly open?
Any thoughts greatly appreciated.