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4d56t overheating Q's


Vai-Man

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I brought a 96 l200 4x4 turbo diesel non intercooled a year ago.

It had a new head belts water pump etc with all receipts done by diesel and turbo, about 30k ago.

First issue was it got to about 3/4 on the gauge going over arthurs pass 6 months ago, didnt think anything of it due to the massive hills and being fairly loaded topped up the water and all was sweet, 3 months later going over the dessert road and round the lake to omiri it got quite hot again spiting coolant out the overflow but after coasting back down the hills it cooled down a bit so i refilled and bleed the system and it was sweet getting back to wellington, replaced radiator cap thermostat and flushed the system.

This weekend another 2 months after the last incident, i went up to ohakune and it was pushing coolant out and getting warm by waioru so i stopped and let it cool filled up and went 30 kms to ohakune bleed the system drove it around seemed ok so headed back started getting noticeably hotter on the climbs out of taihape over viniger hill and into feilding let it cool in palmy at a mates house and was ok back to wellington.

It is bubbling into the expansion tank and out the rad when the cap is left off, it pushed out about a litre from palmy to welly and seems to get hot when you have a long climb or start pushing it above 100ks.

Any ideas? BHG? where can i get a coolant test in wellington?

tldr; mitsi diesel overheats probly a BHG :x

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I would be looking at the thermostat with those symptoms - sounds like its not opening enough or blocking off a bypass port or somthing - replace it with the correct one and also check for any leaks in the cooling system. I have a pressure tester if need be.

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Since you say it has a newish head elimanate radiator first, remove it and have tanks removed to flush it out propertly.

Then remove/check/replace the head. Sounds ruthless but I've probably replaced 30+ heads on those things over the years, they're dirt cheap new and an easy job. They're are not as bad as Toyotas where the head is throwaway and you can normally see the cracks without pressure testing, so it may survive. If so use a genuine head gasket.

Retorque it about 3 times also.

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Since you say it has a newish head elimanate radiator first, remove it and have tanks removed to flush it out propertly.

Then remove/check/replace the head. Sounds ruthless but I've probably replaced 30+ heads on those things over the years, they're dirt cheap new and an easy job. They're are not as bad as Toyotas where the head is throwaway and you can normally see the cracks without pressure testing, so it may survive. If so use a genuine head gasket.

Retorque it about 3 times also.

this^

on any of the receipts does it mention the radiator being serviced? often iv seen other workshops/people repair a cracked head/bhg without addressing whats caused it in the first place. whenever we do a headgasket we wont give any warranty unless the radiator is serviced and thermostat replaced at the same time. often its the customer being a tight arse and trying to save those final few dollars that makes trouble for the next poor bastard that owns it.

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My toyota curren cracked the top radiator tank, was running around farily hot a week before this << symptoms like yours gradually gets up to hot then quick drive would drop down. Took it as being major, bought water pump, thermo stat etc ready for re-doing the head and stuff. Turns out radiator was blocked guy reckons up tp 95% blockage. Check the radiator first.

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how many kms on the clock, most go at around the 250000km mark,

i replaced the long block on my delica, bloody expensive to do on a cramped van,

once the head gasket goes once they seem to do it over and over, the bolts stretch and it never seems to run right again,

do the radiator test, but my money is on the head gasket

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Has around 290,000km on it had a new head and gaskit at 140,000 then again at 265000 it has a full history and around $6500 worth of recipts with the last job inc rad recore, new head, headbolts, seals, belts, water pump, alt, injector pump etc.

Well i whipped out the thermostat and ran some powerball though the system, The coolant came out bright green like the day it went in there and the flush didnt seem to bring out anything, i will get it cleaned and checked by a pro anyway for peace of mind. Whos good? Abel smith? capital?

I also checked the thermostat in a bowl of boiling water it only seemed to open 2/3mm so im guessing that aint right ill replace that tomorrow. Took it for a drive down the gorge and back up around jville got to about half way on the temp going up in 5th. which seems alright.

I can see good coolant flow accross the rad but it still filled up the expansion tank and pushed about a litre out of the radiator, could that be the cap? the rubber seal doesnt look to bad, ill replace it anyway.

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if the cooling system is being over pressurised then sounds like combustion chamber gasses are getting into the cooling system. Do a tee kay test to check for CO2 in the cooling system which should confirm BHGitis.

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bugger, sounds like you got a bit of a lemon,

do the basics first, rad cap, thermostat etc

but that bloody 4d56 motor is a notorious for blowing, as you already know by the looks,

i'd be tempted to look about for a replacment engine (not 4d56) and put that in,

i was going to put a Mercedes-Benz OM611 engine in mine if it ever blew again, but poor delica got stolen instead :(

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so long as the cooling system is up to scratch the 4D56T is a fairly reliable engine. Just like a Toyota 2L-TE or 3KZ-TE, once you overheat them then you're up for head gasket and head issues. The post 1991 4D56 engines are much better than the earlier ones which tended to snap camshafts.

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Yea i pulled the thermostat its still pushing heaps of water out its just turned brown and frothy so pretty sure its the head and its gone between a water and oil galley now.

Time to price up a replacement head etc and sort some time to do it, any cheap cars for sale to get me to work in the mean time :lol:

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  • 2 weeks later...

my mechanic puled the head off, said it had gone between the water gally and bore on cylinder number 1 right next to the head bolt. funny thing about that is the headbolt was missing a washer. he reckons thats probly why it went there. the guy who replaced the head last time obviusly missed it

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