Engine overheating

Check the radiator if its clogged-up and water pump circulating coolant thruout the engine if both okay try bleeding the cooling system don't work get it block and pressure tested.

16 or 18 psi it doesn't matter versus the OEM part the idea behind it is to hold that pressure

Did they pressure test the old cap? Again block test it and go from there that's if the water pump and radiator are in working order-could be very well be airlock in it-who knows?

Could be low on coolant, that would be the most inexpensive. Before I spent any money to address it, I would strongly recommend the cooling system be checked for the presence of combustion gases. This would indicate an internal leak, and could bein the range of $3000 or more to fix properly.

In my honest opinion, I am not real supportive of additives, but I am in the repair business. Will it work, I don't know. I have never had any experience with anyone who has used it.

I will give you this scenario. Assuming that it has an internal leak, the cause is aluminum thread failure in the head bolt holes. Could be one, two, or several, on one or both banks. A sealant is possibly going to help the current leak, but will not restore the retention(clamping) of the stripped hole. What is likely to happen, is holes around the stripped one are going to fail, as they are more relied upon to sustain the load. This comes from heating and cooling, expansion and contraction.
A lot of the reason I don't support additives, especially in the cooling system, is this. You add it to a tank, with not alot of turbulent water flow. The heavier portion of the substance is likely to settle to the bottom. If in fact it does make it main stream, is the leak bad enough that it is going to seek and plug it? I have seen more of the sealants trapped in the bottom of radiator tanks, and blocks. It could lead to increased cooling system temperatures, and a higher potential for overheat.

The assumption that you have an internal leak is just that at this point. You would need to have it tested to confirm. A block test is best done with a gas analyzer, like the one used for emissions testing. Roadtest the vehicle until warm, have the gas analyzer at the filler when the cap is removed. Any reading over 100 PPM hydrocarbons indicates a cause for concern. As far as Steel Seal, on a consumer basis you could give it a try. If money, or repair costs exceeding the value of the vehicle are a concern, it is your best option.

Don't waste anymore time, or money, until you have a block test done for the presence of hydrocarbons in the cooling system. Aside from the occasional thermostat stuck closed, failed W/P belt tensioner/belt, and low coolant level, internal combustion leaks are the major cause for overheat on these engines. The head bolt threads in the block were a poor design from 93 up until about 2004 when the thread pitch was increased.

Coolant does not flow through the intake manifold, nor would it cause an overheat. There is a passage through the throttle body that can plug and possibly cause an overheat, but it is somewhat rare. If you are not confident in who is giving you the diagnosis, and they have yet to do a block test, I would urge you to demand a test before spending anymore money. If they don't know how to perform the block test, or are not equipped, find someone who is. I would be willing to bet that it has leaking head gaskets(internal) due to pulled head bolt threads.

Hi:
If you replaced the t-stat, chances are it is ok. If the fans are working, they sound ok. Does the engine cool down when the fans turn on? Have you ever had the radiator flushed?

Let me know.

Joe

Your engine coolant temperature sensor could be faulty. Have it checked/replaced. This sensor, tells the computer what the temperature of the coolant is so that it will turn the fans on when it becomes too hot.

If a wrong cap were used and was to high of a pressure, you could blow a hose, because of too much pressure.

If the pressure is too little than nothing will happen, other than it will release the pressure sooner than what is recommended.

May want to try bleeding the system.