ZD30 Pressurized cooling system

[DaleB]

Morning All,

I am fearing the worst, hoping for the best...

Weekend had me travelling to Nelspruit area. My Madman started screaming at me for low coolant level every time I stopped (two screws in the pressure bottle). When moving it stops screaming. What I found is that the water is being pumped out my pressure bottle into the overflow bottle to the point where the overflow bottle overflows and the pressure bottle is empty. When she cools I transfer the water back to the pressure bottle and all starts again. she does not seem to be "using" water or at least not very much. All the water is being caught in the overflow bottle.

She did not overheat once. My madman shows water temp in the top hose, still reacting to the EGT as it always has. Climbing with EGT of 500deg odd the water temp climbs to 91deg, with the water temp dropping back to 87-89deg or so on the other lower EGT bits. So I am confident that there was always water in the pipes.

No other ill effect. She pulls great! Starts easy. No smoke. No steam. Other than pumping the water out the pressure bottle all seems normal. I fear cracked head or blown head gasket.

Also, I hear from G Tech's answering service that they are away for a while. anybody else come recommended? I want to try get the Motorrite warrenty to pay for this which means I cant do it myself.

Thanks,
Dale

[SCUBA Patrol]

Dale,

try replacing the pressure cap on the radiator! (the spring on the pressure cap might be worn)

[Tinus lotz]

Go to nissan order a 1.2 bar cap and have a look again.....
Lets see if its sorts your problem....

[DaleB]

Graham replaced the cap at the last service, +-5000km's ago. The problem has escalated from a few months ago (last service where Graham replaced the cap) where the water was not being effectively pulled back into the pressure tank to now where the water is being pressured out the tank (still not really pulling back).

Its a new Nissan cap.

[Chris Skinner]

I sincerely hope its not the case, but my neighbour had similar problem on his Pathfinder diesel.
After much misdiagnosis by Nissan and trying different radiator caps etc.... turned out to be a hairline crack in his head (pressure forcing water out the bottle and into the overflow bottle).

[ricster]

Yeah, I'm thinking the same Chris.... I would get the Patrol to a Silvertons or reputable radiator place and let them do a exhaust gas in the water test. A tiny crack can make major nonsense. The good thing is that, although the head will need replacing ( if it is infact the head that is cracked) and it will cost a few bob, there is noting wrong with pistons and sleeves and bearings etc.

DON'T GET THE HEAD METAL STITCHED !!!!!!!!!!!! this on a diesel doesn't work. The compression ratio is far too high in my opinion. If you use a non genuine head, make sure that the water port and all channels and ports are open properly. Alternatively use a genuine Nissan head. Also use only a genuine Nissan head gasket and coolant fluid. This was advice I got from Frans ( Tour de Frans ), and that man knows his stuff !!!!

Graham will definitively be able to help you sort this out too

Maybe check the radiator too, could be a small leak on the plastic header or bottom of the radiator itself, causing a loss of pressure, making the water boil too early, and allowing air back into the system when the car is turned off.

[DaleB]

Thanks. Head is also my fear.

Can Silvertons and these guys accurately check for leaks? I have not had any success with them on any of the vehicles I have ever had tested.

Also, in the way of aftermarket heads, what are the better options and where to source?

Graham is not here till CW43. I would rather have this sorted sooner than that.

Had my radiator flushed a few months ago and it was reportedly quite blocked. Wonder if the previous owner had overheating issues? Would explain the root cause...

[petrol]

The only people I can sugest is cme (centurion motor engineering), not sure what their number is but they do good work from my long ago experince, was'nt on a patrol though

[Kagiso II]

Dale - 1: Replace the bottom water hoses [there are two] you will only find them at the Nissan dealerships no aftermarket / pirate available for them .. and they are murova pricey
2: Get another Rad cap [1,2 bar] they do fail, even sometimes comes as dud .. Again, get the real mcCoy from Nissan -- the copper thingy of the after market [Midas et al] are not the same size.
3: while replacing the hoses, flush the radiator
4: IF the problem persist, have the diesel pump calibrated [BOSCH agencies tend to be the better option for that.

5: If still doing the same, replace the pistons -- [have them inspected anyway -- the ZD 30 is infamous for OVER-fueling and that burns through the piston tops and that "hand granades" the engine .. so really, remove the heads and check the pistons anyway [save you BIG money to prevent that engine going KAPOW !!

6: IF the pistons need replacing, get the replacement set from ALERT Engine spares [Pretoria West .. but they have branches ..
IF [IF IF] the head has cracked, also get it from ALERT .. Remember, the ZD 30's Engine number is stamped on the head .. NOT the block, so do have your registered engine number stamped onto the new head ..

Oh -- and lastly: get the proper head gasket , the METAL one
LASTLY - take you bakkie to Turboworks and have the turbo checked and serviced.

Throw away the exhaust and replace with a 63mm free flow with NO silencer boxes

By the way .. If the CATS are still in the exhaust, ignore all of the above, have it removed first and replace the exhaust [In my view best place to have that done is SAC Boksburg]

Once the heat soak and water flow problems are solved, have that engine dyno tuned

Cost of all of the above ?? About 10 - 12 K .. MUCH much less than engine overhaul
Lekker slaap

[Michael]

In my opinion your problem has nothing to do with your fuel pump, injectors, pistons, turbo or exhaust.

Pressure in the cooling system can only come from one of two places, a crack in the cylinder head or a head gasket that is leaking.

You can make one last attempt and make sure you dont have any coolant leaking somewhere. I think Silverton can do a pressure test on your cooling system which will confirm either a water leak or a cracked cylinder head/head gasket issue.
You can also try a new cap as well as its not that expensive.