Pinzgauer D24TIC

[v8volvo]

Originally Posted by PINZ 716

Have you checked your rad. I would change that after the thermostat and water pump. Even to the point of changing the Rad first after checking out that the other 2 are working..

Hecklebone's evidently stays pretty cool most of the time, except the needle climbs a bit when pulling a long hill on the hwy at WOT. I bet your guess on the rad is a probably right, either that or avoid doing the climbing on the highway, which sounds like it is working so far. Pinz rad doesn't look much larger than what is in a Volvo, and the engine enclosure is a tight space so I don't think there is much airflow around the motor, probably a factor as well. I imagine the cooling margins are pretty slim for WOT climbing with increased boost and fuel, even when the rad is perfect.

Hecklebone stopped by over the weekend and we bombed around the neighborhood a bit -- sure is quieter and smoother without the intake sitting against the interior panels...! and moves quite well with 19lbs of boost. I am headed out near Gunnison CO to do some work on another 718 6x6 TD on a ranch up there next weekend: will be interesting to compare it, since it's stock, at 8000' elevation, and has a fully enclosed ambulance body so probably an extra half-ton of mass to drag around.

[PINZ 716]

The D24 engine as you know was originally built by VW and licensed to Volvo. I read somewhere that the VW built engines are slightly stronger than the Volvo ones I could be wrong.

I find that the VW dealers are the best place to get engine parts from. I have the Pinzgauer workshop manual both civilian and Ministry of Defence ones on CD and on my computer which really comes in handy. Some of the engine operations carried out are slightly different than the Volvo ones.

VW upgraded the thermostat to a higher degree one. The Pinz manual gives 3 temps 71-80-87 for different countries the 87 was fitted in the earlier VW Euro engines. Now replaced with a 89 or 90 degree one from memory.

Manual shows air valve at the top of the thermostat for letting trapped air out of the block. I bought two last year for Pinnie's that I was working on both from VW both with the air valves in. One of the old ones that came out didn't have the air vale in.

Also the rad cap was changed from I think 1.3 bar to 1 bar to help temp wise.

I will now only fit VW water pumps due to the critical cooling problems with this engine. I don't think the problem is as bad in the Volvos as it is with the Pinzgauers, possibly due to the fact that the engines are fitted a long way from the radiator so the pump has to be a very good one. I know 1 Pinz guy that had a Pinz jacked up in the air trying to get air out of the system while they bled it.

[745 TurboGreasel]

Originally Posted by v8volvo

Hecklebone's evidently stays pretty cool most of the time, except the needle climbs a bit when pulling a long hill on the hwy at WOT.

My Volvo has done that with 4-5 different radiators.


My VW dealer,
"What 6 cyl diesel?" "What is an LT? I don't see anything in the computer."

[ngoma]

PINZ 716, Maybe I misread, but it seems that fitting a higher-degree tstat and reducing the rad cap pressure are both counterproductive to reducing overheating issues.

Also: What problem does the tstat with the air valve solve?

[PINZ 716]

The thermostat with bleed valve in helps to get air out of the block when filling with coolant

The lower pressure rad cap means less pressure build up in the cooling system
Higher temp stat will get engine warmer before stat opens. The quicker an engine warms up before having to be cooled improves the efficency

If you have a problem with your temp increasing when climbing I would say you have a radiator problem. When the engines is hot after a run feel the rad all over any cold sections will mean a blockage

You also have to remember that this engine fitted to the Pinnie due to its location will behave slightly differently to one fitted in a Volvo

[ngoma]

OK, I get you now. Interesting. We were talking about overheating at one point in this thread, yet VW evidently made some changes could worsen an overheating tendency (higher temp tstat and lower pressure rad cap).

[PINZ 716]

Originally Posted by ngoma

OK, I get you now. Interesting. We were talking about overheating at one point in this thread, yet VW evidently made some changes could worsen an overheating tendency (higher temp tstat and lower pressure rad cap).

I understand what you are saying but with a higher temp stat the engine will be more efficient as the heat on its first few miles is making the engine more effiecent and keeping the oil cleaner before the stat opens. Otherwise you would just take the stat out and not bother with it.

Rad cap being lower pressure will be less likely to overheat. Try running a vehicle with the rad cap off it will take a longer time before the system gets hot. So a lower pressure rad cap will keep the pressure in the system down. Yes the higher the pressure the better the cooling as the water is pushed around more.
But as we all know the cylinder heads on these engines have always been a problem certainly in the Pinzgauers

[v8volvo]

Interesting points, but I'm not so sure about some of this. Since you are right that cylinder heads and headgaskets on these engines can be a trouble area, and keeping them out of trouble requires careful and smart cooling system maintenance, we want to make sure the info people read (and act on!) regarding this subject on the forum is not confusing or controversial. In that spirit, maybe we should try to make sure we all agree about some basic things.

One thing we know is true, as physical fact: lower system pressure will decrease the boiling point of the coolant = not good for cooling. It will make the engine *more* likely to overheat. Only sense I can see in which lower pressure might help avoid overheating is if you have marginal components in the system, like a hose that you are worried may burst at higher pressure. In that case, running a lower-pressure cap may help avoid a sudden catastrophic coolant loss that could cause damage.

However, in terms of normal cooling system performance, higher pressure is a benefit, *especially* if you are choosing to run a warmer thermostat. A hotter-than-stock thermostat plus a low-pressure radiator cap is, IMO, a risky combo that creates a possibility for serious problems. If you've had success doing that -- in a Pinz no less! -- then I am interested to hear about any other changes you may have made to the cooling system at that time as well, because unless I and others are missing something, these two things could only possibly impair the system's ability to keep temps under control.

I'm not trying to dispute what you've said, just would like to to encourage a little further conversation on some of these points since it seems like there are couple areas where we're not all on the same page, and hoping we can clean up the resulting information with a little more clarity. Thanks!

[PINZ 716]

Sorry about the delay in my reply I have just got back from a 3 day off roading trip in my truck.

I'm specifically looking at the Pinzgauer set up here and your quite right that the Pinnies have less cooling around them as the engines are enclosed in. It doesn't help that the Rad is quite a distance from the engine so cooling hoses are stretched quite a distance. The air is direct through the tunnel and hits the front of the engine only which doesn't help matters.

I have had a few Pinnies with overheating problems.

Two of these vehicles came from the Malaysian Army and had been sitting in about for a number of years not used, lots of missing parts from them.
On both of these trucks I fitted new timing and injection pump belts so naturally fitted new water pumps while the front was stripped down. Once they were up and running both over heated, one was pumping water out of the overflow when it was ticking over.

To cut a long story short I ended up changing both thermostats from local accessory shop plus a new rad in one due to cold spots across it after road testing.
One was still overheating the other one I had to strip out the engine and rebuilt the block as the pistons had picked up. Fitted it back in again and overheated. Ended up fitting a new cylinder head( the AMC ones) problem solved. While I was working on that and getting the engine parts from my local VW dealer I discovered the thermostat upgrade. VW had discontinued the lower rated stat and now produced the slightly higher one. So I took the view that there knowledge was better than mine.

One of the things that I liked about the VW stats was the bleed valve which should make it easier to bleed the cooling system, certainly in the Pinz. Again in the MOD Pinz manual it shows fitting the Stat with the bleed valve at the top.

It is a lot colder here in the UK so your vehicles may be running on lower temp stats.

The Pinzgauers have had the cooling system changed a number of times now in an attempt to reduce the problems of heat.
If you find it hard to get air out of the system the manual shows to fill part of the cooling system up through one of the smaller hoses coming off the engine.

Again I have only looked at the Pinz in this area not the D24 fitted to the Volvos. Indeed I have been working on the Pinnies for the last 5 years from the petrol 710s, 712s through to the diesel 716s and 718s

[745 TurboGreasel]

My 84 Volvo factory manual also specifies that the bleed goes at the top, implying there is one.