Don’t waste your money.
Remove the radiator cap when the engine is cold.
Start the engine, and as the engine idles, watch the coolant in the radiator.
If bubbles start to form in the coolant, it indicates a blown head gasket.
Tester
Thank you very much for your VERY helpful input @weekend-warrior @Tester @nofyfb_180405 as of right now i have ordered the exhaust tester. i get it tomorrow morning and will be testing in the afternoon/evening. i will light a candle and pray to the head gasket deities this comes back negative. when it hopefully does i will move forward with a radiator vacuum.
This may work but leak has to be significant. For a small leak, you may not notice much and yet it’s sufficient to create air pockets. Especially under load. I had good luck with these chemical tests. At one point, I found a leak in infamous subaru head gasket when there were still no symptoms. When I pulled the head, I could clearly see where it was blowing by.
Good luck!
In this case - even though head gasket is a major repair - it’s better to find the problem than to keep scratching your skull indefinitely.
Not your case but just a piece of nostalgia: I remember dealing with a british sterling (no longer with us, thank God!) that was overheating since it was started the very first time. The dealer tried everything they could think for, nothing worked. They ended up tearing the whole engine apart and found a piece of form sand stuck in the water jacket passage. British cars are indeed something!
Listen to your mechanic. It’s either the water pump or the radiator. Both of those can be tested by doing a “flow test”.
That car had a British body and interior, but a Honda power train.
You don’t believe “it” is a head gasket however your symptoms indicate that the head gasket is leaking. There must have been an overheating event that led to this warped cylinder head/leaking head gasket condition.
It used Honda design but was manufactured in GB by the brits. Devil is in the details.
Just to clarify a couple of points since you stated this problem happened after an A/C compressor replacement.
You reference the fan operating and state that you run it at 2500 RPM to simulate driving, and the fan does come on. Has that been done with the A/C both on and off?
With the A/C on the fan should come on immediately. Does it?
Since the compressor was replaced that brings up a potential high side pressure problem due to an overcharge, faulty expansion valve, etc. Has anyone checked those pressures or even considered that? Higher the RPM the higher the head pressure which means more heat.
I am not familiar with the Cadenza so this is guessing. Many vehicles use a narrow air deflector which mounts onto the lower radiator support and forces air up through the radiator. Quite often they get knocked off due to road debris or critters or possibly removed during a repair and forgotten. That can cause overheating but ONLY when the car is used for highway driving. Idle/slow speed little or no effect.
I did not go net fishing to find out if a Cadenza is so equipped therefore this is theory only.
Briefly scrolled though the posts, seems like the problem is the air flow to the radiator is obstructed. OP mentions using pressurized spray to clean condenser. Guessing that may be the problem, b/c the force of the spray bends the fins over, preventing smooth flow of air through the condenser, which also affects air flow through radiator. If radiator pressure washed too, same thing can happen to it. Photos above in posts 9 & 10 suggest this the problem. Note how many of the fins are bent. May be able to unbend them, but may require removing condenser from engine compartment, which has its own set problems. A/C specialty shop best for that job.
My other guess, subtle head gasket problem. Heat engine to normal operating temp with radiator cap off. See a lot of tiny bubbles coming up through the coolant toward radiator cap opening? Look for that when revi’ng engine as well. Chemical test for exhaust gas in coolant another test to consider.
Well F#$%. i do see those bubbles, i assumed the whole time it was trapped air
@nofyfb_180405 . ( i was banned from replying last night because you apperently cant post more than 21 replies on your first day. im doing the test since i had already ordered it either tonight or tomorrow morning. ill reply back with results.
I am also going to replace a coolant fan resistor based on a video i saw online. i dont think it will fix the issue im having but it still needed to be fixed.
i know the air deflector your talking about and no my car doesnt have it but that would have def been something to look at thanks!
thanks for the reply, testing it out tonight with the chemical test.
Suggest to not automatically assume air bubbles in coolant mean head gasket problem. If coolant recently replaced or cooling system opened to replace some part etc, that can lead to a good deal of entrapped/dissolved air in coolant, and cause bubbles to appear. Can take several weeks after cooling system work for all the entrapped air to move out of the coolant. Chemical test + result along w/bubbles however would strongly suggest head gasket problem.
Replacing the resistor won’t hurt but - if I recall correctly - you stated that cooling fan does come on properly @ correct temperature.
As a rule of thumb, I am not a huge fan of throwing parts in without knowing for sure what the root cause is. It is possible - unlikely but possible - that the new part (especially electric/electronic) is defective, and you end up chasing your tail.
Let us know how the head gasket test goes.
Good luck!
Yeah what everyone said. I’ll just add that a radiator can get coated on the inside too and lose cooling capacity. The faster you go,the more strain is put on the cooling system. Like one discussion though, when they changed the compressor did they get the belt back on correctly so the water pump is not going backwards?
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@Tester @weekend-warrior welp here it is guys. also a diagram that probably shows why i havent and fluids in my oil or any white smoke out of my exhaust.
didnt turn yellow… but def changed color @nofyfb_180405 when i checked the resistor it had a crack and a little piece of it broken. so it had to be replaced regardless.
Like I said, replacing the resistor shouldn’t hurt.
As far as color goes, have you looked up online what people are saying?
Test result looks ambiguous to me. Seems inconclusive. Any change noticed in the amount of bubbles in coolant? Any signs of melting gaskets on underside of cooling system pressure cap? Have you asked someone to follow you in another car as you accelerate up a freeway on-ramp at full acceleration? Sometimes with head gasket problem, white smoke out the exhaust pipe only occurs then.