6.5td GMC Installed in a Gulfstream Sunsport Rv

[rvray]

We have suffered terible over heating problems with this vehicle and been through a multitude of suggestions from people. finally after changing the radiator for the second time we seem to have sorted the temperature thing out ,however the system seems to be blowing the water out of the second expansion tank and blowing air bubbles on idle! Has anyone got any sugestions ? It has a strange cooling system with a large rad and single stat. Mounted above that is an expansion tank with a pressure cap rated @ 14psi. Entering this tank is a 1/4" pipe from the radiator overflow. There is also a 1" pipe feeding the top of the water pump and a 1/4" pipe coming off the neck of the expan tank leading to a small water bottle(Non Preasurised).When the engine is running hard the water from the main expan tank gets drawn into the engine but as soon as you release the accelerator back to idle the tank fills back up to the max mark and blows all the water out of the second bottle, Has anyone come across this arrangment before?
Any ideas anyone PLEASE !!!!

[rjschoolcraft]

I am afraid that you have a compression leak into the coolant system...either a blown head gasket or cracked block or head.

Significant improvement in cooling system performance can be gained by incorporating the upgrades discussed in this article. (http://www.thedieselpage.com/members/features/65cooltipsc.htm)

[rvray]

Thanks for reply,
Is there anyway of checking without a strip down?
This was a rebuild in July 2004 and has only done about 1000 miles since! It doesn't seem to be making any oil or loosing the water through external leakage, only what it blowing out of the second bottle.

[rjschoolcraft]

If it is "blowing air bubbles at idle" (I assume you see bubbles in the plastic reservoir), then that is a typical symptom of the problems I mentioned earlier. However, some of the other symptoms could also indicate incomplete bleeding of the coolant system when adding coolant. If it were not for your "blowing air bubbles" comment, I would say that first.

I'm sorry that this is not a very good diagnosis. :(

[rvray]

Yes it is blowing into the second unpresurised bottle ( Like a screen wash bottle). I have not seen a motor with this type of arrangment before,ie: a rad and two bottles, it just all seems a bit odd to me ! Do you know if this is specific to Rv's ? There isn't many around over here to go and look at, but a friend of mine is a bus mechanic and works on Scania, Volvo, Gardners and Leylands but hasn't seen this either?!
I will try checking the cooling for air again as you suggested. I have seen somewhere on the site that this can be problem in the V8's,is there anyway of bleeding the front end of the engine or should it clear itself? I have blead the heater matrix as this is right at the front of the vehicle and is at the highest point but even they are fed front the thermostat end of the engine.
Thanks for your help so far, I am open to any suggestions to try and avoid stripping it down again !!

[MTTwister]

Seafish - I assume that you've bleed air from the thermostat housing already? There should be a Brass screw on top of the housing to allow you to bleed the air. Otherwise, no helpful hints. Good Luck, and Happy New Year.

[rvray]

MTTwister,
Thanks for reply,but there isn't a bleed screw on the stat housing, But the top of rad is higher than the engine so I am assuming that if it is full it should clear itself!? Not sure!

[rjwest]

Didyou have the problems before the rebuild????

Sounds like something maybe installed incorrectly.

Assuming no Compression leak into coolant...
Pull the thermostat and recheck everything,

Also, you may need a good high flow Thewrmostat.
Since it's a motor home. the coolant tanks are
probably non-std GM

Might try RV forum's for help.

Or send a note to RV manufacture.

[More Power]

If the cooling system continues to build pressure beyond the 14-psi cap rating, I agree with Ron that you may need to investigate a cylinder compression/combustion leak into the cooling system.

Head gaskets are the cause for most of these sorts of problem.

A cylinder leak-down test could show which cylinders are affected. Most mechanics worth their salt can do this for you.

If I might make a recommendation..... If the engine needs to come apart for new head gaskets, I'd recommend using the info found in the R&R Guide (http://www.thedieselpage.com/rrad.htm), then follow the 6.5 cooling strategies outlined in the article Ron linked to above. We've been through this enough times to know what works - including for members with a 6.5 motorhome.

MP

[rvray]

rjwest,
Thanks for suggestions.We have allways had a cooling problem.The rad was re-cored to start with but it turns out that the new one fitted by a local company was not man enough for the water pump flow, so we have had it done again by a different company and that has deffinatly cured the hot running temperature problem,and the blowing the water out of the little bottle only occured when the engine finally went POP! It would not supprise me if something else could be installed wrong as when we bought the long block assemble from acompany that rebuilds these engines specifically after fitting you could only run it for about 10 minutes before the temperature was in the Red! After changing thermostats and taking them out bleeding the system etc, I came to the conclusion that something was wrong with the new water pump that they had also installed before delivery. After stripping all the rads back out and removing the water pump it was found to be the wrong rotation, For a Vee belt drive and not a Serpentine Drive,Despite stating clearly the intended application proir to purchase.With all this in mind it could have done a head gasket so I think that a starting point now would be some sort of compresion leak test as suggested, to prove a point one way or another.
The tanks are definatly not Gm style and as you say probablly Rv suited.The gm dealer also suggested Head Gasket even though he was a bit confused by the tank setup on this motor.Thanks!

[rvray]

MP,
Thanks for the link to the R&R guide, just ordered one! I think that we will start with a leak test following everyones suggestions. I did check out Ron's link when I first subscribed and spoke to a very helpfull chap at Kennedy Diesels but because this engine is a "Pusher" and not a"Puller" some of the mods like the fan clutch would not be suitable and it was thier initial suggestion to have the Rad checked over again, however some of the other mods like the Dual stats can only help.Definatly worth considering if its coming apart again! Thanks.

[rjwest]

I think there is a " Exhaust leak detector "
that goes in coolant system when running thet will detect exhaust blow by. ( not sure, help from someone on this ).

If there is a " head gasket leak " I would go to installer, parts person for some " expense "
money, A backwards pump can cause overheating
in the cyl heads.....


Also: if not losing any Fluid and not overheating,
The bubles in the second tank may be " somewhat normal" for the motorhome.....

There " cobled together " systems were not always the best....

May get better after all the air is out of system......


Also: are they sure Water pump is now the correct one. and is the thermostst a " High flow "

Would not run over 180 deg stst on a motorhome.

May try removing the thermostats to see if any help.


You are running 50/50 mix of antifreeze/coolant?

Again , Try the RV forums and ask about model/engine. Probably some help there/// Good luck.

[More Power]

The national Safari Trek (http://www.trektalk.net) group manager (NTR) contacted me in early 2004, prior to their annual convention about providing some books for their free drawings. According to their records, 42% of all Treks have the 6.5L diesel engine. You might try contacting them for related motorhome information.

However, we tend to specialize in the 6.5, and we have quite a few Trek owners as members. We even did an article on a 6.5 powered Trek a couple of years ago.

MP

[rjwest]

Reading again: Try blocking off the Heater line..

sounds like radiator path restricted and heater
line is filling tank

[DIRTYBIRD]

Hello fellow RVer. My '93 Safari Kalahari pusher always had marginal cooling. My latest round of modifications was to remove every other member in the grill, cut nominal 8x16 inch vent holes on each side of the main grill (behind decorative trim) and add after shrouds that isolated the hot air that came from the radiator. These changes have dropped my indicated engine temperature about 30F, to about 165! I'm very interested to see if this holds on a hot summer day.

[DmaxMaverick]

I scanned through the posts and didn't see anything about it, so if I missed it, put me in my place.

Does your engine have V-belts, or a serpentine belt? The V-belt turns the water pump in the same direction as the crank and accessories, the serpentine belt is opposite the crank and accessories. If you have the wrong pump in place, it could certainly cause your condition. The fan/clutch has to be matched to the direction, also. Is your fan a pusher, or puller? I'm not familiar with your rig. Is it a rear engine pusher, or a puller with the radiator behind the grill? Could be important info.

[rvray]

Dirtybird, Thanks for reply. We allready have a metal shroud around the fan which guides the air from the engine out through the rad and then through the rear of the vehicle. Just for interest we have considerably reduced the coolant temp by having the rad re-cored,Turns out that they may look the same but can have a totaly different configeration inside.It also had an alluminium plate across the lower half of the grill restricting the passthrough of air, which we have also removed! As another point about the type of rad,piggy backed on the front of the main cooling rad are the two oil coolers, Gearbox and engine. One thing that we noticed when the new one came back is that the direction of the cooling fins are the same on the three rads now, where as before on the coolers they went left to right but the main rad they were vertical, which in theory should allow the air through easier again.

[rvray]

DmaxMaverick, thanks for interest and suggestions. We had this water pump issue in the first instance,See posted 01-05-2005 05:37 AM. and hopefully this is resolved.

The engine is setup at the rear of the vehicle as a pusher with the gearbox to the front and the fan at the rear blowing the air out through the rads and out of the back of the vehicle.
The fan is solid bolted through an alluminium boss and onto the water pump flange directly so there is no fan/clutch, but thanks anyway.
Any suggestions welcome in case there is something we have overlooked !!

[rvray]

rjwest, Thanks again ! In the coming week i will try blocking off the heater pipes first and then try and do a leak test as suggested. I have also looked into the cooling mods but unfortunatly the RS 180F stats are currently out of stock,but if we have to strip it down again we will probably go the distance and change the pump,stat and crossover pipe for what it costs !
Thanks

[Salemone]

Seafish,
One of the problems with a PUSHER is the source of cool air for the radiator. Does your rig have air vents on the sides? If not all the air comes from under the vehicle and across the HOT engine.
I have a PUSHER too. 78 degrees outside and I probed 118 degrees into the fan. Will be coating all exhaust manifolds,turbo and exhaust pipes with JET-COAT ceramic coating for the summer in Southern California. This should keep the heat in the exhaust system and away from the radiator.
John--

[rvray]

Hey Guys,
Just to let you all know, We pulled the engine apart last week and it had a blow across the head gasket from No 2 to the coolant bore!
Just as the R&R book descibed it!!!!
Whilst its apart we are also going to go for the cooling mods as suggested and see how we get on.
I will put another posting up when we have finished, hopefully with the conclusive results,but it will be a couple of weeks by the time we have rounded up all the parts !
Cheers