2.8 turbo diesel running too cool? cold?

[gomulletgo]

Hi everyone,

My truck is giving me trouble, I've had it a while now and it always used to run at 1/2 on the temp guage. Recently I removed some EGR stuff on the truck, see the link below for more details:

viewtopic.php?f=29&t=1393

The day after I removed the EGR stuff I flushed out the radiator with water, after flushing it out with water I drove to chch 50kms away appx on the highway I noticed the temp was only at 1/4 so I took the next exit, checked the radiator, the water was low, I topped it up and drove on, the temp never rose above 1/4 so I pulled over and checked the radiator again, it was still full.

I should state here that the radiator water has been rusty since I bought it and I want it sorted. I'd flushed the radiator with water several times before this temp issue arose.

A mechanic friend suggested rust had probably jammed in the thermostat holding it open (keeping the engine too cool) and that I should put cardboard in front of the radiator and heat the engine up to just over 1/2 (to dislodge the rust), I did this, as soon as I took the cardboard out the temp dropped back to 1/4.

So I replaced the thermostat, while the gasket sealer was curing I decided to take out the radiator and give it a good hose out, I did this, it ran dark brown, heaps of rusty water came out, not really big flakes but plenty of rust. I sent it to the local radiator guy for a good clean out, but he said it was shot, so I put a good second hand spare one in (I cleaned it heaps first, inside and out)

When I put it all back together with the new thermostat and much better radiator I took it for a decent drive, same issue again, only 1/4 temp on the guage. My mechanic friend was stumped, One of the EGR vac hoses (that went to the intake manifold valve blanked area) was producing a vacuum, so I blocked it. That didn't help either. We thought maybe the viscous fan was locked up all the time, keeping things too cool, it wasn't, when temp was at 1/4 with the engine running the fan could be stopped by hand.

Concerned the guage or sender was faulty today I bought a cool radiator cap that has a built in temperature guage! (old one the rubber was a bit perished) When the dash guage is showing 1/4 temp the temp at radiator is nearly 80C or about 170F that seems low to me, I thought the temp was supposed to be about 95C can anyone tell me what is right?

Cool radiator cap with temp guage.

PICT0393edit.JPG

Today was a warm day 25C upwards, I checked my heater while driving it seemed to pump out plenty of hot air.

I'm totally stumped, is it still safe to drive the truck until the issue is sorted? Is the problem likely cooling related or is it more likely EGR removal related?

Thanks heaps in advance.

[Captcol]

My truck runs a little cooler now with the egr removed, I think that is because you are not reintroducing already heated exhaust gases back into the system. Will check today to see where it is sitting on the gauge. Sorry this is no immediate help

[lewis]

Well well, my truck has been in the family since 94, normal operating temp is 1/4 on the gauge, its been to half way before when there was a water leak lol, and it was def overheating!
I thought 80 degrees was bout normal?
Im fitting an aftermarket water temp for piece of mind (along with an EGT gauge) for piece of mind when tuning and offroading, so when i get round to that I can report back on temps, im slow so this might take a while haha.
Also it does rise a little above 1/4 when foot flat going up long hills, but never near 1/2

Whats your fuel consumption? Id imagine if the engine isnt up to heat then its not as good as it should be. I get 11.3km/L ish standard rims/tyres, fuel not turned up, standard exhaust, standard airbox with that stupid hose that goes across to the battery removed.

My radiator is a piece of poo also, the bottom half is rusted out and you can push the core into a crumble with your finger and no force. However im stingy with money so havent replaced it as never overheated due to that yet, and after a long run the bottom of the rad is cold as anyway. Im thinking this might change when Im offroading lots though due to lots of revs and not much airflow. Time will tell. My coolant is nice and clean, but I replaced a water hose to the turbo last week and it was rusty inside haha.

Sure geeves can add his 2c also with same truck.

Lewis

[turnturn]

My temperature gauge runs about 1/4 to 1/3 nearly all of the time (UCS55). I'm not sure what this equates to in actual temperature.
I notice that you have a 90 kPa (13psi) radiator cap fitted. Have you tried using one that has a lower pressure?
Lower pressure = lower boiling point. It may run a bit hotter?
I like the radiator cap (good for problem solving), where'd you get it?

[geeves]

Life doesnt work that way re the cap. It runs the same temp but might boil sooner.
1/4 is the normal for the isuzu diesel. Mine runs there except on slow hills but there will be a separate post on that with a photo of the radiator in the next few weeks

[muzila]

My 2.8 runs cooler after I removed my EGR valves as well. I would be very lucky to even reach 1/4 on the gauge. and I get very little heat from the heater nowa days.

I too like that cap where did you get it from and how much?? That would come in very handy!!!

[gomulletgo]

My truck runs a little cooler now with the egr removed, I think that is because you are not reintroducing already heated exhaust gases back into the system

I'm hearing this a bit from the people I'm asking about it, it makes sense to me. I guess my main concern is if we are all running our trucks at lower temps than the factory intended will our engines wear faster? Consume more fuel?

Sorry Lewis I have no idea what my fuel consumption is. I should've really checked it before and after the EGR blanking.

Hey turnturn, the radiator cap that was on it was 15psi so this cap is already lower, not on purpose, it is just the radiator cap/temp guage the guy in the store gave me.

The cap is made by CPC (I don't know who they are) I bought it from BNT in CHCH central but it was the last one, so maybe try another BNT.

Muzila as above, I think it was just shy of $37 the guy did it for me for trade.

Hopefully I'll have my boost and EGT guages in soon

Cheers guys

[geeves]

thermostat is 88C Radiator will be cooler than the engine so under light running that temp looks fairly right.
Ive seen what happens when you run a higher thermostat on a different engine.
It was an LT1 in a cruiser. split a bypass hose on a slow downhill. The result put Putu geyser to shame. The whole cruiser just disapeared in a steam cloud. We had to wait an hour before we could even touch the engine.It then took 7 liters of water to refill after repairing the hose. We wernt sure there wasnt another leak so tried running it with the cap loose. It boiled within 5 minutes downhill. Everyone was glad I carry 6 liters of water just in case. The other liter came from someones thermos so he didnt get coffee that day

[Drift]

5 years with this truck and its never gone over the first white line 1/4, well only once when I had a bust water pump.

Granted its cooler weather here but even at 25 in the summer on an 8 hour trip in traffic it never moved above 1/4 thats with then without the EGR's .
Most over here are the same, I would panic if I saw mine head to halfway on the gauge

[geeves]

Only time mine cleared the half mark was when the viscous fan died. Got to 3/4 on a slow long climb even with heater on full. Water turned brown it the radiator so its fair to assume it boiled

[98Rodeo]

well my rodeo ute stays on half or just a touch below all the time, does drop towards a quarter if its left idling for too long
have seen it go over half once when the alternator/water pump belt let go! had to be on the freeway with nowhere to stop didnt it!

[youngtruckie]

im having the same problem with my mu to my temp gauge dose not move at all unless im in low range crawling up dunes. i cant figure it out either!

[geeves]

Rough and ready test if you have brass radiator tanks is to put your hand on the tank at normal running temp. If you can hold it there a few seconds before saying ouch its about right. If its no hotter than you bath water its a little cool. If it hurts straight away it might be a little hot. If it takes the skin off straight away its defiantly overheating.
Dont try this with a plastic tank as its always cooler. 80 on the tank will feel like about 50 if you were to put your hand in water 90 would feel like 60. Remember burn cream is not recommended on burns but cold water is.
A proper test for the thermostat is to take it out and put it in the wifes best cooking pot and cover with water and if you have one put a thermometer in with it. You heat it till it opens this should be 80 to 90 on the thermometer or about the same time as bubbles start on the bottom of the pot

[geeves]

Another thought. Guage faults are common. Ive never heard of a confirmed guage fault on these but Nissan patrols nearly all show 0psi oil pressure due to faulty guages

[lewis]

I think its more of a mental concern cause most cars operating temp is 1/2 way on the gauge but it seems mr isuzu wanted to be different.

I used to use that touch method for tuning my nitro methonal r/c 4wd, except touching the heatsink on the top of the engine and it worked quite well. That thing had 3hp i think and weighed like 3kgs yes it was rediculously fast and flipped over backwards and got huge air time and its still broken in my garage, one of those hobbies you just spend too much time fixing not enough time using.

Im waiting for a replacement of the cheapo aftermarket water temp gauge i bought off tm for $15 cause it was a dud, look forward to getting some real temp numbers - they really shoulda included them on the gauge from factory too. Will report back with numbers when its sorted.

Only time mines been to half way was with a perished leaking hose.

[electrifying]

My temp gauge used to work ok, then i fiddled with it & now only reads 1/4 normally, and 1/2 when very hot.
I went 4x4ing last weekend with a 4wd club, the day beforehand i installed a second temp gauge to monitor the engine & ended over-tightening it & cracking the thermostat housing , anyway, going up a big steep long hill the factory temp gauge reached just over 1/2 of the way, and my second temp gauge was reading 95C, & water boiling in radiator (due to cracked thermostat housing), so i am thinking that the original gauge or sensor is not working correctly.
By the way 4 out of the 5 Nissans on the trip overheated going up the hill & had to stop half way, go Bighorn!

10 IMG_7150.jpg

(photo only shows 3 Nissans, but 4 did have to stop for a rest)

close-up of nissans overheating.jpg

(I thought a little spying would be good!)

So as far as i can see, temperature gauge gives a good indication of when the engine will seize, if it gets to the far right side, engine is probably seized. Middle is boarder-line too hot, 1/4 is about right.

[lotusfrontera]

Mine normally reads between 1/4 and 1/3. But after a weekend off roading it climbed to halfway . Even at high speeds on motorway. So I removed radiator and flushed out BETWEEN fins of rad, now back to normal

[geeves]

was it as bad as mine?
radiator shouldnt boil at 95C for 2 reasons. First a 1/3 mix of antifreeze ups the boil point to 118 then your 15 pound cap should give another 10C or so on top of that
Thats unless that hill was a lot higher than it looks and higher than any of the port hills

[electrifying]

If i calculate this, according to Wiki, boiling point decreases 1°C every 285m of elevation.
If my temperature was approx 95C, then 5*285 = 1425m elevation. A topographical map shows the height as 1200m, therefore the gauge is probably out by a few degrees.
The other two points that you raise,
firstly the 15 pound cap, the pressure was escaping via the cracked thermostat housing,
antifreeze, i only ever put about 250ml of antifreeze in, + some already in the radiator but looked weak before adding more, definitely not a 1/3 mix. By that time of day when i was heading up the hill, 3L of water had already been added into the radiator which would have further diluted the antifreeze mix.
Hopefully this explains the (approximate) 95C boiling point. The gauge was just a cheap one, so i don't expect it to be linearised properly, or accurate, so could even be out by 5C.

I saw the photo's of your radiator, looked like one solid lump of mud. You must have gone through some deep thick mud

[geeves]

Thick mud doesnt coat the radiator as it doesnt get through the grill. Thin mud does but it takes a few coats before it looks like that