Outer Limits 4x4 Board

Right!, now why does my MK SD33T run realy HOT only when it feels like it??? even in different weather hot or cold days, goin slow or fast, easy or cainin the sh!t out of it and then other times it'll run sweet in all the same conditions???????? PLEASE HELP me i'm goin friggin nuts tryin to fault find the prob.
SO FAR,,,,, i've fitted a new genuine water pump, genuine thermostat, new rad (to suit sd33 turbo etc), reverse flush, cleaned out the block, oil cooler, and air con, new fan and fan-fluid coupling, fitted a 14" thermo in front, had the head off- crack tested it and clean up, new injectors,
also tested compression-o.k, checked turbo main seal-o.k, changed fuel timing- made no difference.
also big exaust fitted (thought baybe to much back pressure).
checked all brakes are not draggin, clutch dosen't slip,
OH MAN I"VE TRIED EVERYTHING THAT I CAN THINK OF!!!!!!!!!!!!
oh and yes i have also had 3, yes 3 different temp gauges and all top brand name and they all tell me the same story!!!
i love my nissans but this rig is tryin to turn me to the dark side
PLEASE HELP ME??????????

Hoses can be a worry if they are old and soft, sometimes they can collapse.

I did that as well, new top, bottom and bypass, i thought maybe the bottom was colapsing under higher revs and coolant demand so i fitted an internal spring to the hose to stop this, BUT still to no reward for my efort

whats the air flow like in front of the rad?

Is it getting the full amount of fuel, and not starving from time to time? The pick up isnt blocking is it, or has dirty fuel filters?

I was also thinking, might want to get an aftermarket gauge with a new sender put in, just to make sure it is actually running hot, and not just a fault with the sender/gauge..

Is the air flow actually getting over the motor? I heard that Thermos are not as good as the factory fan with a shroud..

Maybe think about a scoop over the turbo to increase the flow of air through the engine bay...

at the moment its running an autometer machenical gauge (capilary action) and its the 3rd one ive tried, it dosen't have the electric one anymore.
as for air flow through the rad it'll suck small cars into the front if your to close! it still runs the fan & shroud + the thermo for added flow, it'll hold a full sized beach towel against the grill at idle.
i've also removed the bonnet heat blanket (the one under on the under side of the bonnet).
as for fuel flow, i think it would just drop in power being a diesel, asthe more fuel =more heat,
the filters get changed every 5,000ks. the fuel flow from the lift pump is well within spec. thanks heaps for the ideas though
keep em comin

the only time mine gets hot is sittin in traffic
but thats because my thermos have broken and running no fans atm
i can if i have to just run wire from one thermo to battery if i need
i should get it fixed lol

when mine sits still thats when it cools down (after a bl00dy long wait!)

the thing is i can be drivin in low range in the mud at realy high revs for a long time and it'll be all sweet, then pull out on the road 50 in third gear on flat road, no load, little to no boost at all, then just start gettin hot (as in 98-100+'c) then i'll have to stop and let it cool down,
(and its only run 5-6 psi at full throttle)
then it it's good again or sometimes it'll get hot straight away again.????

oh man it sh!ts me to tears

nicksamaniac wrote:at the moment its running an autometer machenical gauge (capilary action) and its the 3rd one ive tried, it dosen't have the electric one anymore.
as for air flow through the rad it'll suck small cars into the front if your to close! it still runs the fan & shroud + the thermo for added flow, it'll hold a full sized beach towel against the grill at idle.
i've also removed the bonnet heat blanket (the one under on the under side of the bonnet).
as for fuel flow, i think it would just drop in power being a diesel, asthe more fuel =more heat,
the filters get changed every 5,000ks. the fuel flow from the lift pump is well within spec. thanks heaps for the ideas though
keep em comin

well then, i'll go back to ready, seams like all my suggestions have been covered lol

dont have an air block in your system do you, or maybe some where air is getting into the cooling system, and its clogging the water jackets?

just a thought

are you running std boost?? or is it turned up?

yeah that idea come up aswell, so i tried bleeding the system in different spots around the engine, but still no good, the cooant is always clean even after its run hot,

it dosen't use oil or water and there dosen't seem to be any cross contamination between them

at the moment i'm isolating the glow system as the plugs are getting worse every cold start, my idea is maybe they are coming on durin driving and are causing havok??
so i'm just goin to have a push button to hold on when i start it cold...

see if makes any difference

thanks for the help so far

Reddo wrote:are you running std boost?? or is it turned up?

yeah just standard boost, this rig has a stock engine.
just as mr nissan made it

Sounds like a dodgy thermostat. They are cheap enough so just replace it to eliminate that. Then i would send the radiator out to be cleaned to eliminate that. Your fan may be an issue if it only happens at speed. Ive had the blades twist at speed creating an air dam around your radiator and restricting air flow. Another cheap thing to replace to eliminate as a possible cause.

both the thermostat and rad are brand new, it also has a brand new fan and fluid coupling, i've also tried 4 different couplings (2nd hand) before i got the new one, these are all genuine nissan parts except the radiator.

have you only tried one new thermostat?.

Why not try bench testing it a few times and/or even running without one for a while to see if it changes the symptoms.

yeah the thermostat has been tested in water and measred for opening at a different temps,
running the engine without one is sort of against what i was tought, as the engine will never run at its designed operating temp and wont burn fuel properly.
and when it does run hot the rad wont be able to cool it quick enough as the stat isn't there to regulate flow through it

not 100% on that but its what i was tought.

correct about the t-stat out theroy. did fark all in mine without it. Stayed cool until it heated up then it would go past the point of no return and take ages to cool...

Now how hot does it get, 80, 90, 100De? Possible boost compensator prob maybe. does it blow any smoke when its playin up? Do a flow test on the water pump just to be sure.

sterlo

get it thermal imaged whilst warm and look for hot spots maybe its clogged up somewhere?

get a tune by a diesel mech maybe it is too rich.

hey bud what sort of turbo is it ,is it water cooled or is just the standard oil cooled one

nicksamaniac wrote:when mine sits still thats when it cools down (after a bl00dy long wait!)

the thing is i can be drivin in low range in the mud at realy high revs for a long time and it'll be all sweet, then pull out on the road 50 in third gear on flat road, no load, little to no boost at all, then just start gettin hot (as in 98-100+'c) then i'll have to stop and let it cool down,
(and its only run 5-6 psi at full throttle)
then it it's good again or sometimes it'll get hot straight away again.????

oh man it sh!ts me to tears

What do you have on the front of it? Have the aerodynamics been affected by bar, lift, lights, winch, etc to the point that at speed (50kph+) an airlock or vaccum is created in the front, thus not allowing suffficient air to actually flow through the grill and radiator?

Hey mate, check oil pressure and make sure you don't have an air lock in your cooling system, the best way is to bleed it through the heater hoses.

Regards
Luke

Is the thermostat in the right way, ie if its upside down it may have water pressure keeping it closed sometimes?
Did you use the right gasket in the thermo housing?
Is the thermo fan wired the correct way? is it pushing air or pulling? (They work best when pushing air through).
Is it a decent thermo fan or a junk fleabay unit?
Is the radiator top tank mounted higher or lower than the top of the motor, ie do you have an air lock somewhere in the engine cooling jackets?
Run it till it gets hot then check hoses whilst running it/revving it. They may be sucking in.
Also check that water is flowing across the top of the rad...the new pump may be cavitating and crap (is it genuine or cheapo chinese junk?)

sorry for not replyin, been away workin,
well to answer all the latest question's,

when it gets hot, if i don't stop to let it cool it'll go to point of boiling, so far this has happen 1 time (stuck on the road goin uphill with nowhere to pull over, (moonbi range!, if ya been there?)).

the turbo is the standard item & standard boost, 5.5-6 psi at full load.

i've got a fitting mid way on my heater hoses to bleed air out.

the thermostat can only go in one way, with all genuine nissan gaskets and parts.

on the front is only a bull bar and lights, i did drive it around for weeks untill i got pulled up by the fun natzi's about it, but it didn't help the problem, even tried for a few trips without the grill.

the thermo is a davies-craig unit, only just fits in the front and is 14" dia,
it's in front of the air-con core, and is wired up to push through, & the blades are facing the correct way. (as in the curve)

the oil pressure does drop when it's hot, down to around 16-17psi, it's around 21-22psi at normal temp. (mesured at idle)

it is lifted & has a boody lift but it did all this when it was stock,

the tune is next in line to be done, i am starting to suspect the no 4 or 5 pot, cos it's on its 3rd exuast manifold gasket and when it gets to hot the gasket starts to fail on those cylinders in the same spot, the 3rd time i changed it i stripped the head right down, machined the manifold's so they where exactly flat, and it friggin blew again, so my theory is them 2 cylinders might be way over fueling sometimes?

thanks heaps again for the help, it's good to get help from people without all the dorks that just talk rubbish and cause arguments

GUtripper wrote:Is the thermostat in the right way, ie if its upside down it may have water pressure keeping it closed sometimes?
Did you use the right gasket in the thermo housing?
Is the thermo fan wired the correct way? is it pushing air or pulling? (They work best when pushing air through).
Is it a decent thermo fan or a junk fleabay unit?
Is the radiator top tank mounted higher or lower than the top of the motor, ie do you have an air lock somewhere in the engine cooling jackets?
Run it till it gets hot then check hoses whilst running it/revving it. They may be sucking in.
Also check that water is flowing across the top of the rad...the new pump may be cavitating and crap (is it genuine or cheapo chinese junk?)

the rad header tank is in the factory location (about 100mm higher than the rad).
the hose sucking in idea was one of the first try's to fix it.
and the pump is genuine nissan (believe it or it was the cheapest of all the places i tried to get one !!!!!!!)

nicksamaniac wrote:\
as for air flow through the rad it'll suck small cars into the front if your to close! it still runs the fan & shroud...

Maybe you have a small car stuck in the radiator???

Seriously though, check your hoses aren't sucking down, does the turbo have a heat shield? You probably want one.

there was a hyundai stuck between the tread of my mudies!but i pryed it out with my keys

i did try the hose idea, the bottom has an internal support, like a spring.
i haven't tried the top though as its under pressure from the engine.

the turbo has a small heat shield over the exuast side and it has a massive shield along the underside of the inlet manifold between it and the exaust manifolds.
i'm goin to borrow a heat-gun from my work so when it gets hot again i'll look for hot spots in & around the engine/engine bay. (idea from macniel )

Cut a 2L coke bottle in half and tape it too the radiator where the cap goes. Fill it water and run the engine till its hot and see if its blowing any bubbles. Sounds like it has a head gasket issue. The bubbles may appear as just a very small stream coming through the water but this is all it takes sometimes. In other instances the bubbles may show up in groups as they build up in the engine and then get pushed out through the radiator.

will try this idea in the morning, sweet idea mate thanks
i have crack tested the head but only magna-fluxed it, i haven't had it tested under pressure, but the head gasket it new.

Too easy mate! Im a mechanic by trade so this stuff is childs play! I do get some odd curly ones like this sometimes. Had one the other day that was getting hot, ended up being the radiator that was only 4 months old being half blocked with crap. Goes to show you cant take anything for gospel.