Overheating Y60 4.2 petrol Patrol

[Peter Connan]

Ladies and Gentlemen

Ever since I bought my 1996 4.2 nearly 2 years ago it has had a tendency to overheate under certain conditions. These conditions are primarily when driving relatively slowly but with the engine still working hard at lowish revs, such as up long, steep hills or through deep sand. In these conditions the temperature will continue to rise untill the car boils or you stop to take a rest.
the following steps have been taken to try and fix the problem, but without success:
1) The radiator was removed and taken to Silverton Radiators in roodepoort, where it was dimantled, cleaned and a small leak repaired.
2) The thermostat was replaced (it was found to be stuck partially open).
3) The water pump was removed and checked, but seems to be fine.
4) The cooling system has been flushed several times.
5) The viscous fan (which was busy breaking) was replaced by 2 14"electric fans. The fans are in a cowling and switch on sequentially, the first at 95 and the second at 102 degrees. The system also has override switches that can be used to switch the fans either on or off. (The reasoning behind this modification was that at the low speeds at which the problem generally occurs the viscous fan is turning relatively slowly and therefore is not of much assistance)
6) The mixture has been richened slightly and the timing etc. are regularly checked.
7) The correct anti-freeze mixture has been restored several times.

Most of the major repairs described above have improved the situation, but the problem persists and is too serious to be ignored. During the above work the following additional factors have come to light:
1) The system was operated without anti-freeze for extended poriods, as some of the smaller steel fittings have had to be replaced because they have rusted through, and there was generally quite a lot of rust present in the system.
2) The radiator was repaired with stop-leak or Bars Leaks or some similar solution. I have been told that this stuff can coat the engine internals thereby reducing heat transfer and possibly even block some of the smaller channels in the engine, and that it cannot be succesfully removed with the engine in one piece.

It is therefore my intention to remove and dismantle the engine, and have the block, head and any other suitable components acid-cleaned before re-assembly. The major reason for this is that I am scared that there may be areas within the engine that are not being cooled effectively and that are thus even hotter than the temperature gauge suggests.

I thus have several questions for the learned and experienced people present on this forum:
1) Where can I find gaskets etc. (the local spares shops have been unable to source these)?
2) Should I replace the oil and water pumps?
3) Are there any modifications that I should carry out at the same time? (I would also like to increase the power output somewhat but am operating on a rather tight budget)

Any recommendations would be gratefully accepted and carefully considered. ALso, are there any glaring problems I may have missed?

Regards and thanks in advance
Peter

[David]

Hello Peter,

Quite a job you have planned for 2011!

If you are going to strip everything you can just as well replace the bearings and have new rings fitted while you're at it. If your Troll still has points and a condenser I would also add an Ignitor electronic ignition and coil ( http://www.pertronix.com/prod/ig/ignitor/default.aspx). I do not know how many km's you have done so have your oil pressure tested to see if it is necessary to replace the oil pump but I will definately replace the water pump - as a matter of fact I would replace the water pump first to see if it is not maybe the reason for the over-heating! You mentioned it was operated without anti-freeze for a long time so is the pump moving the water fast enough through the cooling system or is it busted? A faulty water pump can cause an engine to overheat if the impeller vanes are badly eroded due to corrosion or if the impeller has come loose from the shaft.

[Grant]

Peter,


Have found the second seat belt for you.


I would change the water pump. Do not go to Nissan. Call master parts in Cape Town. They have an original water pump for a 5th of the price. Oil pump can be pressure tested. New oil pump is only available from Nissan. For the 4.2 Diesel price is R 5K. No discount available.Mine has done 365k and is still within specification.

For extra performance I would have the head gasflowed at Van Der Linde's ( I know you had problems before, but like is too short to hold grudges). Also do the cam shafts.

As far a pistons and other engine components go, I have been looking for other options with out any luck. Agents seem to be the only answere.

Regards

[AndriesS]

Hi Peter,

I'm not to familiar with the older Patrol's engine layout but here is a couple of things I would look at. I'm not a super mechanic (Frans comes to mind) but have tinkered on some engines:
Normally overheating means an engine is overpowering the cooling system, many a backyard mechanic overboaring his engine will have this problem and the amount of heat generated cannot be removed by any radiator /oil cooler in standard configuration. It sounds like yours is standard and you're sure the timing and fuel is ok so I would look at improving the cooling:


1) Fans
Are you sure the electric fans move enough air? - the cheaper Autozone ones do not move nearly enough air - somewhere on 4x4community someone did a comparison on different electric fans.
Are they sucking or blowing, some people have had better luck with sucking than blowing (fans I'm talking about)
Are they in a proper cowling covering the whole radiator or just shrouded
I've not been able to replace any viscous fan without major effort to get a decent cowling for an electric fan.
Are they moving air in the right direction.
2) Radiator
Have you thought of adding an oversize radiator, with more cooling capabilities. Getting an old radiator cleaned does not always improve the cooling capabilities if it is blocked. Is it and up down or side to side flow? Side to side might be better.
3) Air moving
Can the hot air move out of the engine bay, or is the hot air stagnating around the engine, some guys lift the back of the bonnet to allow air to escape / or move.
any thing blocking the flow such as and AC condenser full of crud, spotlights hooters etc.
4) Do you have the standard manifold or branches? branches tend to heat up the engine bay even more - consider getting them ceramic coated.
5)Waterpump.
Check the blades (not corroded or eaten away )and that the impeller is not spinning under pressure.

[jeanne.volschenk]

Hi Peter,

Master Parts Cape Town can help you with a gasket set.

Regards

Jeanne

[Peter Connan]

Thanks Guys, I will try masterparts a bit later on. Nissan want R5916 just for a gasket set

John just to answer a few of your questions:
I am not sure the fans are really moving enough air, but I am convinced they are moving more air than my viscous fan moved at 3000rpm, however there is no guarantee that that was working 100%. they are generic parts shop fans, and I have been considering getting better ones. They are in a proper cowling I made from 1mm steel sheet, covering the whole radiator and are definately sucking air into the engine bay.

With regard to most of your other comments, as far as I know the engine is standard, and it still has the cast-iron manifold, however I do not have a service history. The only modifications I have carried out are a free-flow exhaust after the manifold and a snorkel on the intake. The water pump is not slipping and although there is some slight evidence of cavitation on the faces of the impellor blades, the edges are still in fairly good condition and therefore I doubt that it is the problem. Also I have been told that you can check the water pump by measuring the temperature difference between the top and bottom hoses and if they are within 5 degrees then enough water is circulating, and this is the case with ny car. Since most of the other guys on the forum with similar cars are not experiencing the same problems, I beleive there is a specific problem with my car, which I would like to fix before I carry out any further modifications. My reason is that if there is a real problem inside the engine then perhaps some parts of the engine are running significantly hotter than the temperature gauge is showing and this may cause me a lot of damage in the long term?

I did experiment in Lesotho with holding the bonnet slightly open by releasing the bonnet to it's hand-catch, to try and get more air through the engine bay, but it didn't seem to make any noticeable difference.

Once the system is 100% correct and I still have a problem, modifications like larger radiators, bonnet scoops and oil coolers will definately be on the agenda.

[Peter Connan]

Hi Grant thanks for the seatbelt, I will get it from you.

With regard to camshafts, would one not be sacrificing some bottom end? The other thing I am considering is increasing the compression ratio from the low 8.3:1 wich is standard to something like 9:1 or perhaps even 9.5:1 (this would require skimming head or block by 1.5mm). Does anybody know firstly whether this is possible and secondly whether the quality and octane rating of the petrol available in the SADEC region would still be sufficient for an engine running a 9.5 compression ratio?

Thanks
Peter

[Grant]

Hi Peter,


After many year of off road driving, all the "petrol heads" love reving their engines. Hardly ever have I seen a petrol vehicle on a 4x4 course drive like our "smokey heads".They love the sound of the vehicle and I must admit, this is on point I miss on the diesel. A friend in Piet Retief has a 2.4 Hilux with a cam that allows him to almost like a diesel, idle over absticles.

With regard to your fuel issue I have traveled in almost every African country in my mining career and have had very few incidents with poor quality fuel.

[AndriesS]

Unless you clearly find the culprit in the engine that causes the overheating, raising th CR will only give you more headaches. Nothing is more annoying than pinging and throttling back on a steep hill or deep sand and unless you take a timing light along and is prepared to constantly tune on your trip depending on terrain and altitude.

As a matter of interest, how do you check you temperature? have you done a compression check? running hot or cold plugs?

Back to the cooling, if you get the opportunity try without the bonnet also see if you can borrow another radiator.

Lastly, do you loose a lot of water, if so check radiator cap for fit (size etc) as well as pressure.


I have a Mazda 3.4l V6 and my first trip was very interesting . in town everything was fine but on the open road after 1hr driving the temp would creep up and in deep sand the car would overheat very quickly. It turned out the engine was very "pap" and after a rebuilt the problems stopped. it was a fairly comprehensive rebuilt - nothing was left unturned but I remained at normal CR's and cams for reliability sake. At the time the re builder changed the viscous to fixed and I also tried the biggest pull electric fan I could fit and never got the cooling better than a slightly dysfunctional viscous, replaced it later with a new unit.
Even in std guise with best petrol available I still get pinking on serious hills like the one on the way to Jozini .
Like I said I'm not too familiar with the 4.2 but here is some ideas of classics I've worked on and the funnies with them -keep in mind on some of these there are 50+years of experience.
Radiator caps - some caps are made for longer necks than other- even though the short neck cap will fit a long neck - the seal will never seat and no pressure will be built.
Thermostats - some of the newer stats don't have bypass stopper (normally like U thingy on it's side at the bottom of the thermostat) .When the stat opens it allows a large percentage of the hot water to be circulated in the head instead of being sent to the radiator.

[Peter Connan]

Hi John

Compression is rather low, between 860 and 930 kPa (manual says 1177kPa standard, 883kPa Minimum), so the engine is getting fairly worn. Oil pressure is still within limits, but also on the low side. There is some blow-by causing sump compression, but not all that much. The air filter remains reasonably clean from oil. Power and torque is also fairly low as can be seen on the free dyno day thread elsewhere in this forum. Therefore a rebuild will probably be a good idea anyway?

I am running standard plugs. I do not lose any water. Also, there is no sign of bubbles or oil in the water or of water in the oil. Normally I rely on the temperature gauge but when I am doing stationary tests I borrow a laser heat-gun from work.

I am also fairly confident that the radiator cap is correct and it is also fairly new. The system certainly builds pressure, as you can feel the hoses become "solid" as the engine heats up, and I blew a radiator hose in Lesotho.

The thermostat has a second small spring-loaded plunger at the bottom, I presume that is the bypass stopper but it is not temperature-controlled, only pressure-controlled.

According to the net, the 4.8 runs 9:1 compression ratio.

Can anybody recommend a good engineering shop in Gauteng? (I seem to be one of those guys who always gets the worst service any provider is capable of)