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Post by justin on Feb 6, 2005 19:40:24 GMT 11
Had an issue arise from my trip to Treachery this weekend. I noticed that under load, (full tilt up an incline on the freeway & on the beach), the temp gauge started to creep up to about 3 quaters. It's never done that before. I have also noticed that the expansion tank is full but yet if I open the rad cap the rad is only 3 quaters full. If I top it up it just flows out the Exp tank when running again? I have since done a descale and flush but there is no change. I know it was in the hi 30's this weekend but it's never done that before so what should I start looking at people? Thermostat? Water pump, New rad?
J
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Post by geeves on Feb 6, 2005 20:18:01 GMT 11
if you fill the radiator then run it and check later and find air in there then there are 2 possibilities
1 the seal on the radiator cap has failed I have had this before but it wasnt bad enough to cause overheating.
2 blown head gasket or worse cracked head. Try filling the cold radiator then leaveing the cap off and idling the engine untill it reaches normal temp. Check regularly from cold for bubbles at the radiator. If there is constant bubbling take both credit cards with you when you visit the mechanic
Good luck
If it is a cracked head I know 2 people that have used ironite to do a cheap repair that has lasted over a year in both cases but both were Ford Telstars with over 300000km on them so not worth doing a proper repair.
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Post by justin on Feb 7, 2005 9:07:36 GMT 11
Sorry Alan didn't quite give you enough info, it's not actually sucking in air, (thankfully), it's actually creating a huge vacuum in the system which will collapse the top hose from the rad when it's under extreme load, this causes the expansion tank to overflow and it loses probably about a half litre of coolant then it stops, but obviously the coolant flow to the engine is somewhat restricted and thus it starts to heat up. I only discovered this by accident as I stopped at a gas station a while back after racing some poor Hilux up a steep hill and I saw a small trickle of coolant coming from under the truck. So I quickly popped the hood and the top rad hose was 2 thirds collapsed. I let it cool for a while then cracked the rad cap and it sucked all the air back in and returned to norm. My first assumption is there is a restriction or blockage somewhere before the water pump which under load causes the pump to increase the vacuum in the system and force the excess out the expansion tank? But I'm no expert with car cooling systems so your thoughts are welcome as the initial descale didn't have much affect. J
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Post by geeves on Feb 7, 2005 10:53:42 GMT 11
the bottom radiator hose is suposed to have a spring in it to stop it colapsing when cold but mine hasnt had since I changed it 4 years ago. It does colapse partialy when cold but as soon as the system heats up its ok.You shouldnt have a vacume in there once hot as the water heats and expands so I would go for a new cap first then maybe the top and bottom radiator hoses esspecialy if they are original. Jackereoo or Rodeo hoses fit but you might have to trim the bottom one slightly to stop it kinking
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Post by justin on Feb 7, 2005 11:15:51 GMT 11
That's actually a good point Geevesy, I never bother to look at the obvious, they are the original hoses and could just be stuffed thus collapsing under pressure. I would have thought a Jackaroo 4JG2 would be the donor. I'll replace the cap while I'm at it. J
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MattMU
Isuzu Senior
Rodeo Now!
Posts: 206
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Post by MattMU on Feb 7, 2005 12:38:22 GMT 11
Justin, definately replace your cap. If it is not recovering from the expansion tank..its stuffed! Any Rad place can check the system pressure setting on your cap(stamped on top 97ish deg) and you know for sure its stuffed! The recovery spring cant be tested, you have to rely on visual. If you just grab a newy, $10 its small insurance. Rodeo hoses (top and bottom) fit perfectly, no trimming req. The rest(oil cooler, heater) are just 14mm (i think) straight hose. Oil cooler is a buggar with the one behind the block and there is another little one at the front of the block from the thermostat housing down. Very hard to get to, I had a pin hole leak in that one and fitted a Torana hose  ? Pain in the butt! Just remember if any hose goes you lose your cooling system, there are heaps. Turbo, fuel injection pump, oil cooler and heater. Hpe you get it sorted mate! Matt. |
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Post by justin on Feb 7, 2005 13:14:27 GMT 11
Thanks Matt Have ordered a new hoses top & bottom main ones first and a new cap. Will give that a burl and see if it changes. J
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Post by Andrew on Feb 7, 2005 18:13:31 GMT 11
sounds like the same issue I had.. unfortunitly mines ended up that there was a crack in the Radiator core.. due to the fan moving forward and taking a nibble out of it..
Had that fixed ( or so I thought ) now a core has split open....
New Rad should arrive Wednesday....
mine only showed problems while in 4wd and under load... other than that the temp gauage was fine...
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RoeDao
Isuzu Junior
If you notice this notice, you will notice that this notice is not worth noticing
Posts: 52
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Post by RoeDao on Feb 7, 2005 19:29:40 GMT 11
i would have put money on the radiator cap being RS....... can't hurt to replace and try again.... my old Commondoor used to have overheating probs until i got a new cap..... it was spitting water out when hot into the recovery tank and not sucking back in when cooled down... new cap solved it
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Post by justin on Feb 8, 2005 12:22:54 GMT 11
Just picked up a Rad cap, upper and lower pipe for the system from Repco, I ordered for a Jackaroo 4JG2 and they are all identicle no mods required, so I will fit them and give it a thrash and see what happens. J
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Post by justin on Feb 9, 2005 11:14:34 GMT 11
Fitted the top hose & rad cap yesterday and gave it a workout up a hill and blew the Turbo feed hose. Thanks Matt! How comes you always know what will happen next  . Anyway drained the system renewed the bottom hose and the turbo feed hose and gave it a blast on the way to work and couldn't get the needle to move past the norm. So we're lookin good. Also checked the battery wasn't squashing the expansion tank feed hose, (thanks JustinW). I guess with the renewed pressure in the system I will find out if I have any other weaknesses very shortly. J |
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Post by justin on Mar 6, 2005 22:54:54 GMT 11
Well gave the old girl a fair hammering at the weekend and I've still got the over heating issue under load??? Changed pipes, caps, now doing a 200kms de scale and if that don't clear it then its either rad, pump or thermostat. Still getting the top rad hose collapsing, (which is a new one too!) yet I'm losing nothing from the system. Its like the return to the pump is being starved under load and creating a vacuum. J PS. Just for your interest I checked the fuel 'economy'  the week before the trip doing 5 days of city driving with aircon and lead foot and got 500Ks out of 70 litres.  On the run up to Gloucester I got 590 K's from 70 litres. So if I can't figure out the over heating I'm dropping a small block Chev in it to get better economy ;D |
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Post by geeves on Mar 7, 2005 18:10:32 GMT 11
Top hose will collapse as the car cools but the amount your decribing sounds a lot. The presure in the cooling system is purly a function of heat and the water pump is designed for flow not presure so unless its leaking its not your problem.
4 things to consider
thermostat You might of changed this but I couldnt find it in the thread It could be sticking If in doubt change it they cost about the same as the cap.
Fan this should rotate freely when the engine is cold but should become a lot firmer when hot. Dont check it with the engine running. There is a silicon liquid in the viscous unit that can be replaced but I dont know where to get it from or how much. A few people here have replaced there damaged fans with Toyota Surf ones.
Auto or manual? Autos are cooled via a cooler mounted in the radiator. Could the auto be causing the overheating. Best talk to an Auto specialist about this one.
Head gasket It dosnt sound like this but it has happened to an Escort I once owned The head gasket caused bubbles in the coolant that insulated the thermostat and I boiled 2 miles out or Rotorua but the radiator was still cold.
Run the the engine from cold with the radiator cap off and the radiator kept full keep an eye for bubbles Contant bubbles is very bad. A freinds surf we tryed this to on the side of the road where he had left it the bubble was so big that water was sprayed over all of us (total cost 4000)
A blocked radiator could also be the cause but if youve always used antifreeze or at least anti corrosive this shouldnt be an issue
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Post by justin on Mar 7, 2005 19:16:05 GMT 11
Thanks Al, I have done the bubble test and that's all good, I'm thinking that its a bockage somewhere, (thermo, Rad, W/Pump), that under load restricts the coolant flow. It has to be extreme load as it happened about 3 times on the whole trip, once at 130Kph down the freeway in 35 DegC, and the other two in V heavy load situations. It cooled back down within minutes and never hit the red so I'm hoping to breakdown whatever it is with the 200Km's descale then if that don't work after I've flushed it I will start replacing parts. J
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Post by draganlada on Mar 8, 2005 19:41:01 GMT 11
Hi Justin I'm not an expert but had some experiance with rads on my other cars and friends cars.If your rad is clogged,or thermostat jammed,or fan and water pump faulty you'l have cooling issues all the time in city driving,but if it occurs only under load I'l check fanbelt tension(slipping belt = les air and water flow at higher engine speed). If fanbelt isn't problem I'l suggest you to seek advice from a professional ( that's what I usualy do; pay $10-$20 for diagnosis then try to fix problem by my self ). However, if your operating temperature at city drive is bit higher then usualy,it can be coused by faulty fan or thermostat or clogged rad. I'm sorry I can't be of any more help  Dragan |
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Post by justin on Mar 8, 2005 20:49:35 GMT 11
That's a bloody good point that I never checked or thought about, and the cooling is only an issue under high revs load. I have a new thermostat now so I will flush the system and replace the thermo and check the belt tensions at the same time. Thanks again. J
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Post by Witchdoctor on Mar 8, 2005 21:04:57 GMT 11
Having the exactly the same problem, only gets hot under load long hills or towing the trailer with slight load. Had al the things done declog the cooling system, new cap replaced the viscus fluid in the fan no improvement also replaced all the belts. Then put it on the dyno looking for answers, this told us that it was over fueling none of the components (e.g fuel pump) have been tampered with. they believed that the injectors would be cactus. It does blow smoke on start up. The price has got me looking in other areas. Have been told to replace the head gasket then look for a larger core radiator. Starting to make MY head spin  . Need to find ijector company local to test the injectors before spending the big dollars have been quoted about $1300.00 to replace injectors. Does this help any? Dave |
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Post by justin on Mar 9, 2005 8:58:36 GMT 11
I remember you saying you had this problem, personally I think it has to do with the Rad, and it will be next on the replacement list if the flush/thermo/belt session don't work. I've only had this problem once before on Stockton beach in a 30 knot following wind when it was 37 degrees. I think the cooling systems on the MU's do not have a great deal of high external temp tollerance, so I will be looking to upgrade the Rad and fan to 'monster system' if I have too. Also you have to take into account I have a bullbar which certainly affects the airflow to the rad. Add all these factors to a bit of degradation in the cooling system and I'm sure you end up with the result we are seeing.
I will post the results as I go. J
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Post by Pissy on Mar 9, 2005 9:27:29 GMT 11
Dave, do you have them 240 lightforces on the bar ?
Could they be interfering with airflow onto the rad?
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Post by justin on Mar 9, 2005 10:26:08 GMT 11
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? Pain in the butt!
.
the week before the trip doing 5 days of city driving with aircon and lead foot and got 500Ks out of 70 litres. 
On the run up to Gloucester I got 590 K's from 70 litres. So if I can't figure out the over heating I'm dropping a small block Chev in it to get better economy ;D
. Need to find ijector company local to test the injectors before spending the big dollars have been quoted about $1300.00 to replace injectors.
