Engine running hot - temp gauge normal?

Hi Everyone,

This is my first time posting to the forum. I've got an interesting issue going on with my 2000 Toyota Tacoma that I'm hoping you might be able to help me trouble shoot.

The engine is running hot. After a 10 min drive the hood is almost too hot to touch. The interesting thing is the temp gauge is reading normal. I took it into the local dealership today to see if they could resolve the issue.

The mechanic drove it and said the hood was crazy hot and the engine was running too hot. However, after checking the thermostat, water pump, coolant, hoses, fan, radiator, etc. They couldn't find the cause and simply handed the truck back.

Needless to say I'm less than impressed. Historically I would be able to trouble shoot and work through this on my own. But I suffered a TBI and have lost most of my mechanical knowledge/skills so I have to rely on others to do the work for me.

Does anyone have any ideas on what the issue could be?

I just moved to Asheville, NC if anyone happens to know any good shops nearby.

Thank you in advance for any suggestions you may have!

 

Buy a scan guage and you will know 100 percent the actually temp of the engine, takes 5 minutes to install

 

As a professional we have reservations about throwing parts at a problem, but this is actually a problem and it needs to be figured out.

I would suspect the radiator for restrictions and coolant flow.

Next I would check for headgasket failure and combustion gases causing overheating.

 

Thanks for the quick responses. I'll order the scan gauge tonight. I forgot to mention the dealer did flush the coolant and said there were no restrictions. I completely forgot to ask about the headgasket. I'll add that to the list for the next shop.

Thank you!

 

The gauge is center deadened to make it seem normal through much of the range of running temps that could occur. Unfortunately that is most unhelpful when diagnosing a real problem.

 

Did the mechanic check the coolant temperature sender/sensor? If its reading wrong (low) so you may not really know your coolant temperature. When you get your Scangauge check the engine oil temp it should give you a clue if the water temp is ok.

 

Just be careful not to drive it much if at all until you get a temp reader hooked up (like a Scangauge). Your dash temp gauge might not be reading accurately and you don't want to be driving the engine too hot or you could do some serious damage. Even if the needle isn't at the 'red' it could still be hurting the motor, those gauges aren't known to be very reliable.

 

Mine too is starting to have temp variations. (I have the scan gauge.) It usually runs at 191 and never budges, but crept up to 220 sitting in concert traffic on Saturday. (Eagles ) I have a new water pump and thermostat and coolant is OK and full. I also need to check the radiator for flow as I am about to cross into 200k miles.

My question is this: If there is a head gasket leak what is the best way to tell? I know to look for oil in the coolant and there is none when I remove the cap. Any other ideas? This may help both of us out. I'm very mechanical as well, however valve cover gaskets and manifold gaskets are as deep as I want to get into my trucks engine.

OP the Scangauge is an amazing tool to help spot problems early. The dash gauge is designed to show "normal" through a range of temps. It will only show "hot" when above the set threshold. They were designed like this to prevent regular folk from panicking when the temp on a normal gauge would go up 10 degrees.

 

Leak down test can verify, I think there's also a kit that can test for c02 in the coolant which could mean a bad head gasket.

This article has a lot of good info on head gaskets.

https://barsleaks.com/gaskets/symptoms-blown-head-gasket/

 

i run at 196 all day long... the temps vary a little bit for people on this site, as do the needles

 

Run 188-190 all day long even in 100 degrees outside temps.
But sitting still in traffic temps go up to 195
You have to have a scanguage to know what your real temps are not the stock needle guage.

 

Thank you everyone for your valuable feedback. I greatly appreciate it!

The scangauge arrived today and I plugged in, but can only get the water/coolant temp.

Does anyone know the codes for engine temp or oil temp?

I have a first generation (2000 toyota tacoma 3.4, manual) and can't find them anywhere.

Thank you again for your help!!

 

If you cycle the buttons the water temperature icon should automatically be in there for the engine

 

I was able to get the water temp. Is there anything else you recommend looking at?

Thanks!

 

I've never heard of diagnoising an overheating engine via the hood being hot.

Maybe because Florida sunshine makes the hood a griddle anyway.

Glad you got the SCII. It will tell you the actual coolant temp, which is what you need to know.

 

The water temp is all you need, the stock guage will not tell you the real temp but the scanguage will

 

If you dont have a temp gauge installed in the truck, the IA (intake air) gauge will get you close.

 

All the heat is generated inside the cylinders which are surrounded by coolant which is surrounded by the outside metal of the engine block. The point is that the outside of the engine will not be hotter than the coolant.

I'm wondering if you have anything covering underneath the engine restricting the air flow. Air should go through the radiator and downward out under the truck.

On the other hand, hoods do get hot unless they have a layer of insulation which these don't. Did you ever actually measure the temperature of the hood?

 

So what is your coolant/water temp?

 

There is a code you can use to access transmission temps. Do a search here and you can find it. It is very handy to see as well.