New to me truck/coolant issue

[bowtie_6.5]

Hi newbie here,
Ive done several searches and have not found anything that parrallels my situation, so bear with me if its be answered before. I just recently (two days ago) bought a 1995 6.5l td 2500 2wd std cab w/ utility bed w/ 150,000 miles.
The truck for 11 years old is astonishingly clean and well taken care of, and NO rust for being a jersey truck (kinda odd). The carfax states the truck was a fleet vehicle until I bought. Now to my Problem/story, Picked the truck up 1-1/2 hours away from home. Noticed the coolant was low (added a gallon) and double checked all fluids before leaving to go home. Truck ran great except for a slight miss on big hills, and noticed a mist (coolant overflow/boil over) once or twice (verified visually at rest stop). The whole time the temp never went above 170 and was constant, also when I turned on the heat it was barely luke warm the whole trip. So I get the truck home and took a look in the coolant resivoir and it was low again, so I added another gallon, and then out of curiousity I thought maybe this thing doesn't have a thermostat in it and is airlocked or something. So I pulled the stat housing and bam no stat!!! So I go and get a 195* stat and gasket and install it, refill the system and bleed it suffieciently, take it out for a spin and is slowly climbs to 230* and then boom it drops like a hat to 185* and at the same time the heat comes back in the truck. Obviously the stat opened but it continued to do this until its been run for 25 min or so. Parked the truck and bled more air out.
Runs ok but still some temp surges, it did the same thing this AM and it seems like its just plain airlocked. Also if anyone knows the coolant cpapcity of 6.5l I would appreciate it. So any thoughts? Also I ran some Cetane Boost/cleaner and it runs like a champ no miss!!!

sorry so long winded

[Trek 6.5 TD Pusher]

I've seen this happen if the thermostat gets put in upside down. Any chance that happened. The flat part of the thermostat should be up I believe, putting the temperature sensing element down in the engine.

Ken

[bowtie_6.5]

Im pretty sure, The spring is down and the flatter side is up, i thoguth thats how it was installed? lol maybe not. Also just to add, I thought maybe its loosing collant in the motor, but as far as i can tell the oil is clean, and no vapor is at the tailpipe.

[DmaxMaverick]

Welcome to the Forums!

What brand thermostat did you install? Anything other than the OEM or Robert Shaw (or whatever brand replaced it....check with www.kennedydiesel.com for the latest/best) will cause issues with temp stability, and higher temps under heavy load.

How's your coolant tank doing now, after the stat install? Keep a close eye on it! Also, confirm you have a functioning cap, and replace it if you have any doubt. A missing stat and/or disabled pressure release would indicate to me the previous owner had ECT problems, and possibly a blown head gasket. Removal of the stat and disabling the cap is a pacifier that will get the truck sold. Usually, by the time the new owner figures it out, it's too late. Just a 6.5 caveat. I suggest a coolant system pressure and compression test first thing. It may have only been a stat issue, but catch a head gasket or head issue early, and you'll get many more miles out of it. Not to mention reducing your time spent on the roadside.

[winemaker]

I just had a coolant flush done a month ago and he told me it holds 27 liters. I don't have a calculator handy, but divide that by 4.54 to get gallons. Off the top of my head, around 6 gallons? Brett

[bowtie_6.5]

The levels seem to be okay now and the air is bled out, the brand of stat Im not sure of. When you speak of ECT problems what does ECT stand for (acronym). Also what tell tales are there of a head gasket going bad on a diesel, Im a gas engine wrencher mainly and usually its milky residue in the oil and/or heavy vapor at the tailpipe. Any ideas of coolant capacity on these hogs?

[bowtie_6.5]

I just had a coolant flush done a month ago and he told me it holds 27 liters. I don't have a calculator handy, but divide that by 4.54 to get gallons. Off the top of my head, around 6 gallons? Brett

thanks, actually the coversion is more like 7.1 gallons @ 27 liters, I have a weights and measure calc on my pc here at work.

[DmaxMaverick]

Capacity is about 7 gallons.

Milky oil is a good indicator, but these engines will usually have serious issues before seeing that. A typical indicator is uncontrollable ECT's (Engine Coolant Temp), excessive overflow/surge tank level fluctuations, and coolant loss. The symptoms are dependant on on which system is leaking into which. If it's coolant/cylinder, you may never see oil contamination or tailpipe vapor. It doesn't always leak both ways, meaning, you could have cylinder pressure leaking into the coolant, but no coolant leaking into the cylinder.

[bowtie_6.5]

well thanks alot for everyones input, i'll check it all this afternoon and keep this thread updated!

[Dvldog8793]

Howdy
Hate to bring this up but it could be a cracked block...When I diagnossed my block I pressure tested to 16psi for about 6hrs then cracked the drain plug and water was the first thing out. The new antifreeze will mix with oil and coat the insides of your engine and you don't see a huge increase on the dipstick. It does sound like you have head issues but don't discount the block as they have been known to crack also.
L8r
Conley

[DmaxMaverick]

Howdy
Hate to bring this up but it could be a cracked block......

Obviously a possibility, but I wasn't going to say that just yet. Everything else should be checked first. The issue could be the stat/cap only. When we see block cracks that cause coolant loss, almost all the time, there will be coolant in the oil. He said he didn't see that.

[bowtie_6.5]

Yeah, the Oil is clean, it needs to be changed its real dark almost black, but it doesnt feel sticky nor does it look or have any evidence of other fluids in it. Plus with amount of coolant I had to refill the oil level would be way beyond overfull, Im hoping its a simple stat issue, but after thinking about it and Dmax's input, deductive reasoning makes me feel its a head gasket.
(1) coolant loss, and lack of stat to begin with, the other owner def had problems, which is exactly why I have a Freaking nice truck with a $6500 Stahl Grand challenger body and in great shape for $5,500. Which I was Prepared for when I bought it.
(2) New stat is in but the ECT is all over the place and it seems like air pressure keeps building in the System. Which explains the overflow on the high way when the temp never got above 175* w/ not stat in. So to me its like one part/side of the head gasket is leaking air in the coolant system while the other side is slowly losing/burning coolant in the cylinder, which concludes a loss of coolant with no visual evidence and air left behind in the system, which I just remebered that the main hose from the stat housing to radiator was tighter than a balloon with no stat installed on the ride home!!!???

[DmaxMaverick]

Pressure in the system (ballooned hose) indicates the cap isn't venting prematurely. It doesn't mean it is working properly. Too much pressure is not good. If the cap is bad, it can allow the pressure to get too high, then remain open too long (not sealing right away), dumping coolant. I suggest replacing the cap as part of your diagnostics, regardless of its appearance. If an option for release pressures is available, go with the lower.

[moondoggie]

Good Day!

In Dvldog8793's defense, Bowtie 6.5 may have a very short window in which to take this up with the seller, if he has any recourse at all. I'd remain optimistic too if it was just another of us with a new problem.

Blessings!

[DmaxMaverick]

In your situation, you are money ahead. Good way to look at it. If you find serious problems, you'd be better off with a high quality repower, like Peninsular, and don't look back. That would depend on how long you intend to keep it, and what you expect in a few years.

[bowtie_6.5]

Well even if it is a head gasket (which is probably is) Its not the worst of scenarios, like a crank prob (knock on wood). I def would hate to have to replace the engine, $$$$ , Plus Ive change enough head gaskets and repaired intake manifold leaks on 5.7L gassers that I could probably do it in my sleep by now. So Ill get that cap changed out as well, and go from there. It be a shame for this thing to have any major problems, because other that the coolant issue the truck runs awsome. Tons of get up and go.:)

[Bnave95]

Your T-Stat should look like this. Nice and long;)
http://www.kennedydiesel.com/detail.cfm?ID=130

[creweldragon]

I had a problem with my TD 6.5 several years ago. We tested for exaust gas in the coolant. It came back positive.

The problem was a crack in number 8 cylinder head.

Hope this helps, but I don's wish it on anyone.

Bob Baker

[Mark Rinker]

Wouldn't a '95 have TWO thermostats?

[DmaxMaverick]

Wouldn't a '95 have TWO thermostats?

No. Dual stats came along on the late 1996 model year. 1997+ will have them.