How to diagnose overheating issues – guide

Share on FacebookShare on Google+Email this to someoneDigg thisShare on RedditTweet about this on TwitterShare on LinkedInShare on Tumblr

One of the most dangerous issues to the engine is overheating.

If your Pajero overheats, try to diagnose the issue causing it as soon as possible, replacing/rebuilding the engine is extremely expensive and it woulds be better to avoid it.

So, how should we do that?

First, have a look under the hood:

1. Check the coolant level – Is it in the right range? if it is not, we should identify why it is missing.

2. Check the coolant itself – Is it clean? is there oil in it? is there rust there?

3. Check for leaks. have a look under the car, look at the hoses and their connections to the radiator/thermostat/engine. Remove the air inlet and look at the water pump, are there any leaks around it?

4. Is the coolant really boiling/hotter than the regular temperature? if the coolant level is fine and the coolant is not boiling and your car is the Pajero/ Shogun NM, then you might have the faulty temp gauge issue, that would be the bast case for you, you can find a quick and cheap fix here, on our site, read how to fix a faulty temp gauge article.

5. Look at the hoses, are they dry and need to be replaced?

6. Is the EGR connected in your car? coolant loosing might happen due to a problem in the EGR cooling system, the symptoms are similar to a broken head gasket.
You can blank the EGR and discard the cooler, then you’ll be able to see if that is the cause.

Here you can see the EGR cooler (with the bypass):

egr-cooler-w-bypass

If you have oil in the coolant, that is probably one of the more expensive issues, it might be the cylinders head gasket in the good case and a crank in the head/engine block in the worse one.

Still, even if that happened, you need to understand the cause before fixing (or, after the fix, but before running the engine again…)

 

Next, understand the situation of the overheating, was it under load? fast road driving? standing in traffic?

If you haven’t replaced your thermostat during the last year or two, now would be a good time to do so. The thermostat is a cheap part and it has a critical rule. You can’t verify that it works fine without taking it out and if it is already out, put a new one instead ๐Ÿ™‚

You can learn how to replace the thermostat in that post.

Next suspect is the radiator, it might be clogged and dirty. Have you ever cleaned it? what is the color of the coolant? is it clean? how old is the radiator? do you see rust in it?

Most of the overheating issues are being solved while cleaning the radiator or replacing it with a new one (read about how to replace your radiator hereย ).

If your Pajero overheats while driving on the free way, then I would suspect the radiator and water pump.

ย Check the water pump:ย well, taking it out and see is the most reliable way, but, usually, bad water pump can be detected without taking them out: look at it, do you see coolant around it? try to shake it a little, does the pulley move? any play there? does it make noises while working? if any of those answers is “yes” then you better replace the water pump.

Otherwise, send your radiator to a good clean…

Last, but not least, the fan clutch.

testing it is pretty simple, while the engine is hot, ask someone to turn off the engine while you are looking at the fan. If the fan continues to turn after the engine is off, your fan clutch has to be replaced. A proper fan clutch will resist the turn while it is hot and the engine is off.

DO NOT TRY TO HOLD THE FAN WHILE THE ENGINE IS RUNNING!!!

DO NOT TRY TO STOP THE FAN WITH YOUR HANDS WHILE THE ENGINE IS RUNNING!!!

We will publish a guide of how to replace the fan clutch and water pump soon.

Notice, that usually after replacing the fan clutch the Pajero is thirstier on fuel at about 5-10%.

One more question that usually pops up is “where should the pointer of the temp gauge be?” usually, it should be at ~40% of the scale of your temp gauge.

Something like that:

temp-gauge-1

hood

Share on FacebookShare on Google+Email this to someoneDigg thisShare on RedditTweet about this on TwitterShare on LinkedInShare on Tumblr
86 Comments
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
    • saar
      • saar
    • saar
    • saar
    • saar
    • saar

Add a Comment

Your email address will not be published. Required fields are marked *


*