Still running Hot!

Trinker · Post by **Trinker** » Thu Jun 22, 2017 10:40 am

I'm stumped, I've now replaced the Water pump, Fanclutch, thermostat, radiator and rad Hoses on my 92L300 (283000) and no matter what I do the second I load the gas pedal at all the heat guage starts picking up fast. Even little hills taking me to the middle zone of my temp guage. I've now checked the accuracy of the guage by monitoring the true heat of the engine with an infrared thermometer and it's indeed running hot (gets up to 235f) going up even a small short incline on the highway.

This all suddenly started happening one day in March (I idled the van for about an hour the day before with the heat blasting to dry it out on a rainy island camping trip) and set me on a mission to solve it before it gets any worse. Right now I have no signs of fluid mixing, I'm not losing coolant or blowing white smoke or none of the tell tale head/headgasket issues. I do have a miss on one cylinder when it's cold but it smooths out quickly after firing up.

My question for the deli forum is, what could suddenly cause my engine to be producing this excess heat? Is it possibly a super minor crack in the head? Or faulty injectors? They were replaced two years ago alone with an injector pump rebuild. Someone please help me! I'm obsessed with solving this and won't sleep well until I have Apollo back to mint running condition!

Post by **Growlerbearnz** » Thu Jun 22, 2017 3:00 pm

Mine never used to move above 1/3 until I replaced all the things, now it does what yours does. I suspect something to do with the temperature sender- maybe the old one was lazy with age, maybe the improved coolant flow exposes it to hotter water. It sits at about 1/3 around town, slightly higher on the highway, up to half going up hill, and the highest it gets is about 3/4 after towing the caravan up a steep hill for 10 minutes. I figure as long as it's in the white "normal" range, it's ok.

235F is a bit more than I'd expect though. At that temperature the gauge should be just about pegged at H. Is that at the radiator top tank, or the cylinder head? Not that I know what temperature the head should be, but for future reference...

You've replaced the radiator cap too, right? (it's the only thing I don't see in your list).

Trinker · Post by **Trinker** » Thu Jun 22, 2017 4:44 pm

I took all of my temp reading from the head immediately beside the temperature sender. I haven't replaced the temp sender itself but it's working fine. I would never want my needle to go above halfway based on my temperature readings however. That would be cooking the engine for sure. I have an EGT coming in the mail here now, hopefully that gives me a more accurate idea of how much heat the engine is truly producing. New rad cap as well...

Next step is to get a coolant combustion gas tester, that should either confirm or bury my cracked head concerns. Like I said, obsessed.....

john clem · Post by **john clem** » Sat Jun 24, 2017 4:39 am

Do you have shroud around the fan?, pretty sure you must after all the work done. check injection pump timing also if you have an automatic trans, there could be a problem causing high friction thus causing excessive heat transfer to the cooling system.

Trinker · Post by **Trinker** » Sat Jun 24, 2017 9:37 am

Fan shroud re-installed naturally. I have a manual tranny and spent much time thinking of the friction issue. I've ruled it out on the basis that if your engine was suddenly working harder two other things would happen 1: You would notice power loss or having to use more pedal pressure suddenly and 2: Your fuel economy would go to crap. I'm still getting 10L/100kms on average here.

You could be right about the ignition timing thing but I have a hard time believing it could cause that much extra heat...

Morgonzo · Post by **Morgonzo** » Sat Jun 24, 2017 3:32 pm

Hi Trinker, I'm currently running w/o a fan shroud (long story and plan to replace asap) and do not see needle movement above the top most wavy line on the temp gauge on hill climbs. When you replaced the thermo and all the rest did you flush with the block drain out? I'm just wondering if a piece of debris has clogged a water passage and is not allowing proper coolant flow thus raising temps. Just a theory.

I was surprised at what came out of mine.

Trinker · Post by **Trinker** » Sun Jun 25, 2017 9:33 pm

I didn't flush the block when I did all the work but I seem to have found my issue. After all that it turns out the system **isn't pressurizing** after all. Classic lesson in checking the basics first.

Now what I have is an entirely overhauled cooling system that isn't building pressure. Swapped the rad cap today and no luck there. So now I just need to find out where the pressure is going and I've solved my problem. Any ideas? I'm not losing coolant, no signs of fluid mixing or any of the other classic head gasket/cracked head issues...

Post by **Growlerbearnz** » Mon Jun 26, 2017 4:13 am

The coolant has to be going *somewhere* when it expands, and if it's not leaking onto the ground then it almost has to be coming out the radiator cap. (If it was going into the engine you'd definitely notice). I wonder if your new radiator takes a different cap to the standard one?

: radiator-cap-a.png (7.93 KiB) Viewed 6101 times

Standard Mitsubishi caps are unusually shallow- the "lower seal" is only about 1cm below the upper seal.
If your new radiator was designed for a taller cap, the lower seal might not contact the sealing surface in the radiator (or with not enough force to hold coolant pressure), and you'll have coolant going out the overflow as soon it expands, rather than building pressure first:

: radiator-cap-b.png (6.94 KiB) Viewed 6101 times

I'd measure the dimensions of the cap and the radiator neck, and make sure the lower seal will actually contact the sealing surface.

You could also try a test to see if the cap is holding any pressure at all: with the engine cold, try disconnecting the small black rubber overflow pipe (goes to the overflow tank) from beside the radiator cap. Start the engine and watch the overflow outlet as it warms up. If the radiator cap is good, you won't see coolant coming out the outlet until the temperature gauge is almost in the "normal" range. If the radiator cap isn't sealing properly, it will start to leak coolant almost immediately- certainly within a minute or two.

Trinker · Post by **Trinker** » Mon Jun 26, 2017 11:10 am

Your spot on Growlerbearnz, took off the overflow hose this morning and she starts leaking withing 30seconds of being fired up. I had two rad caps from the old system, both the same and too short to seal the new rad. Going to grab a new cap today and we'll see how she does. New Radiator is a Fenix. Looks like they're from Australia new Zealand and looks like a much better build then the Chinese ones. Dropped right in, lines up pretty good but needs a different rad cap that wasn't supplied!

Post by **Growlerbearnz** » Mon Jun 26, 2017 2:56 pm

Fenix are pretty common here. Still made in China (like everything) but to a decent standard.

Trinker · Post by **Trinker** » Mon Jun 26, 2017 6:06 pm

I wonder if anyone knows if the Fenix rad cap is different then stock? I found a rad cap today that seemed to seal a little better but it also failed the rad cap test. Is it possible that I have a head gasket leak and thats pushing the coolant out past the rad cap as soon as I fire up? I guess I would be seeing bubbles when running with the cap off and coolant topped up

Post by **Growlerbearnz** » Mon Jun 26, 2017 7:04 pm

I just called Fenix. They don't know for sure, but said that sometimes japanese imports have a different cap to the NZ/Australia market ones. Their radiators are made to suit local market vehicles.

I looked at a local supplier's radiator cap range for the L300. Try a Tridon CB1390- it's 24mm high (others were 21mm high) and alleged to fit the L300 (as well as the Mitsubishi 3000GT, if that helps you to find equivalents). Of course I'm totally guessing, so make sure you can return it if I'm wrong.

Post by **Growlerbearnz** » Mon Jun 26, 2017 7:06 pm

Oh and no, you're unlikely to have a head gasket leak that's pushing the coolant out. If a leak was pressurising the cooling system enough to overcome the radiator cap, you'd definitely see bubbles in your radiator filler neck.

Trinker · Post by **Trinker** » Mon Jun 26, 2017 8:45 pm

No bubbles whatsoever but the second you fire up the engine coolant starts filling into the overflow tank, and when it cools off again the coolant hasn't been returning to the radiator. Somehow air is getting into the system and when you take the cap off cold after driving, the coolant is no longer topped up in the system...

Trinker · Post by **Trinker** » Mon Jun 26, 2017 9:14 pm

So the filler neck depth on the stock rad is 16mm or so. Exact same as on my aftermarket Fenix Radiator... No special size cap should be required...