Temperature gauge reads hot and there is a thumping sound

Hi,

I have a couple of questions. First, did you fully bleed the air out of the cooling system when you changed the thermostat? Also, is the heater working? Does the vehicle ever overheat or is it just the temperature gauge that is moving in an odd way?

Also, are you certain there are no leaks? Have you pressure tested the system? Here is a link explaining how it's done:

https://www.2carpros.com/articles/radiator-pressure-test

Are there any diagnostic trouble codes present? Here is a link explaining how to retrieve them on this model year. You don't need a scan tool.

https://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

Let me know.

Joe

Revving the engine will increase the amount of coolant circulating to help cool the engine, but it shouldn't happen that quickly.

Let me know the engine size and if it's 4wd. I think we need to look at schematics to find this problem. It sounds more like an electrical connection issue.

Let me know.

Joe

Hi,

That helped. I think I found the issue. I was able to dig up an old technical service bulletin related to a temperature gauge/noise. I attached it below. It appears there was a coolant bypass kit that needed to be installed to prevent steam from forming, restricting coolant flow, and then making a noise.

Take a look below at the TSB and let me know your thoughts.

Take care,

Joe

See pics below.

Hi,

No problem. It appears Ford had this same issue for several years. It's the same with 1993, just a different part number.

I did notice that it indicates trying a 16 PSI radiator cap first. If that doesn't eliminate the issue, then the kit is needed.

I attached the TSB for a 1993 below and highlighted the part number. The problem is trying to find one after all these years.

Also, make sure the coolant is mixed 50/50. IF there is too much water, it can cause this to happen as well.

Now for the part, here is what I remember (it's been a while). The kit consisted of a lower radiator hose with a molded-in tee and a section of heater hose that goes up to a new fitting that screws into the thermostat housing where the temperature sending unit is mounted. The temp sending unit is relocated to another part of this new tee in the hose.

I tried for a long time to find a pic for you with no success. Here is the thing. According to the TSB it is caused by steam and we know that it shouldn't even exist. So, make sure the system is flushed, the coolant is a 50/50 mix, get a thermostat that opens at 180 F rather than the OEM 195 F, and make sure you have a good 16 psi rad cap. Hopefully, that will take care of the issue. If it doesn't, we need to figure out a way to fabricate the "kit".

Let me know what I can do to help.

Joe

Hi,

I hope it takes care of it for you. You know, if there is too much water mixed, it could boil and cause steam, so anything is possible.

If possible, let me know if this takes care of the problem. I'm really interested in knowing.

Take care,

Joe

Hi,

It sounds like you found the problem. As far as your question regarding the radiator cap pressure, keeping coolant under pressure increases the boiling point. Since the TSB indicated steam, the maximum recommended pressure cap was suggested to avoid boiling of any type.

Is it possible for you to upload a pic of where it is leaking? I'm interested in seeing it.

Let me know,

Take care,

Joe