The suction hose... If you have a crack in the suction side hose from the surge tank to the cap that would do it.

The old one may look ok, but, have you tried to run a new line from the radiator neck to the surge/overflow tank?

Have you also checked the nipple that comes out of the radiator neck for this hose? Sometimes the solder loosens up.

You'll never find this type of stuff on a psi tester.

Bill N.Y.

Thanks for the additional insight...

The neck-to-overflow tank hose was replaced when I did the cooling system upgrade, as was the thermostat bypass hose and the 1" hose from the top tank to the water pump chamber; all the clamps were replaced where necessary with Torq clamps. I haven't checked the nipple on the third hose at the radiator (3/8" hose from the top tank to the radiator suction-side tank, apparently for bleeding the core itself), but at your suggestion will pull that hose (I didn't replace because that one was relatively new) and take a look. Fortunately, the nipple's in a place easy to resolder.

I pulled the tank today and there was nothing obvious, although the filler neck appears to be a separate piece, plastic welded into the top tank, and the seam looks as if it could be faulty. The way things have evolved, it would be suspect; the weather was relatively cool the past two nights, and the system did pull about half the overflow tank coolant back. That would indicate that the shrinkage due to the cooler temps was enough to seal the leak.

Part of what may make the leak apparent is that the overflow tank is about 14" below the top tank, so the vacuum has to lift as much as 22".

Anyway, the new tank should be here Monday, so I'll put it in, refill and see what happens - I have a series of short trips upcoming in mid-November.

Tomorrow, I'm also going to take a close look at the heater core, as it's in a system high point, but I don't suspect it, as the valve was closed all summer.

quote:

Originally posted by Rusty:
the overflow tank is about 14" below the top tank, so the vacuum has to lift as much as 22".

Now you went and put a bug in my ear. I think I will have to raise my overflow reservoir. Or at least put it on the Twilight Zone list......You know,.......... to do to do to to do.

Well, maybe it isn't a leak in the top tank - there's a dump valve attached to the supply line going to the heater core just upstream from the flow valve; I had used the fitting on this valve to backflush the cooling system. Today I discovered a second, well-hidden, valve on the return - it could be a bleeder as the core is at a system high point, and it could be the GM shop manual procedure for bleeding is inadequate...I'm sure Barth had a reason for putting it there.

So maybe all along it's been air entrainment in the heater....

The surge tank is on backorder - won't be here for another 3 weeks, so I coated the area around the filler neck with Permatex #1, buttoned 'er up and refilled and bled the system including the upper heater bleeder.

But the voyage continues - immediately on cold startup, bubbles start coming from the hose from the the pump chamber, and the pressure rises enough to lift the pressure cap.

So the culprit is most likely a leaky head gasket or cracked cylinder head - luckily, it appears to be a very minor leak. Taking it in tomorrow of Thursday.

The heads are off for magnafluxing - one won't need it as there is a very fine crack visible in the rear cylinder area.

Also going to have the injectors set and the glow plugs replaced while the parts are on the bench.

The turbo bearing seals are also leaking oil, so it's on its way for inspection and refurb.

HI Rusty:
Saw you post that you will probably do a re-man engine, sorry to hear about your troubles, sounds like the engine was worse then expected. Keep us informed of your progress and best wishes for good repair!

Thanks for the sympathy. Actually, it wasn't worse than I expected - it was about what I expected. StaRV II has a very early 6.5L TD, and none of the issues were unexpected (although I would have liked to have gotten another 200K before they showed up ).

None of this is a reflection on prior owners - it's just a characteristic of the stock engine of that vintage pushing this big a load.

But this gives me an opportunity to replace the original engine with one constructed to my tastes, and one that should outlive me. Engines with new (AMG) blocks, latest heads, lower compression ceramic-coated pistons, splayed main caps, and a geared camshaft drive can be had at decent prices.

I considered a DuraMax (360HP) with Allison 6-speed, but I don't know that I want to mess with the conversion ordeal, despite picking up 60 HP and 250+ lb.-ft. of torque. The differential could handle it, but the pedestrian 6.5L TD really has plenty of muscle, although the new one will have about 20 HP more, and add about 40 lb.-ft. of torque. And it will be much simpler than a later 6.5L TD (with the DB4 pump and all the electronics to crap out) or even a late-model (LBZ) DuraMax.

The whole deal, with the new built-my-way engine will be less than $11K installed...

Been there done that on a budget...
I all ready had the phazer gears, intercooler and big exhaust dual stats and high flow water pump. Now have coated pistons and new heads. Since I have the 93 the engine has a mechanical pump requiring one wire, pump is turned up and I drive by the EGT. The engine only had 100k on it when the gasket blew out so the cylinders all looked new. I have new bearings throughout and oil pump which I wish left alone. My oil pressure is less when engine is warm and I blame it on a week relief valve. I did all this and then bought a Barth with plans on selling my 5th wheel. I'm going to tow a couple times just to see how my upgrades work before selling the trailer.

I know your pain, but I've never slipped a engine in a motorhome yet..

btw, what does SOB mean? I've seen it several times....

Doug (I changed my ID from goldwing rider)

quote:

Originally posted by Bywaters:
btw, what does SOB mean? I've seen it several times...

It means...
Something Other than Barth.

A more detailed explanation can be found here.

Rusty, I am sorry that you are having these engine problems at this early moment in your Barth history. I feel kind of responsible because of my pressure to dump the Trek idea.

But hey, you may have had the same problem with the Trek plus a roof leak and cabinets falling off the wall.

It sound like you have it covered though. Can't wait to find out how your custom engine turns out..

The Trek was a '97 - and those engines also had their own sets of issues, and there's no comparison in the handling of the Barth over the Trek.

The repair shop (genuine shade-tree mechanics - they do most of their work in the open) is going to dig a pit, tow the coach over it, and drop the engine straight down, actually much simpler than trying to pull the engine from a puller. While they've done dozens of diesels, this is their first pusher motorhome, and they're eager to see it through.

I'm waiting return calls from Kennedy Diesel and Schoolcroft Engineering on replacement engines.

No doubt, everyone here is waiting with 'bated breath over my choice of replacement engines...

Kennedy Diesel sells only 21:1 compression ratio blocks. Which is odd, because he markets a premier line of 18:1 pistons, used by many other rebuilders (actually he said, like the cobbler's kids, he goes barefoot - he hasn't the time to retro his own long-block/drop-in remans with the lower compression ratio)...

While Ron Schoolcroft makes superb builds (nearly blueprinted engines with tons of HD touches), I haven't heard from him, and Kennedy says he's got a backlog - and generally uses the customer's block (nay, think I).

The first choice now is Peninsular Diesel in MI, which gets the "pick of the litter" of the AMG production. I can get an all-new 6.5L long-block rated at 230HP for less than I budgeted. Since they marinize these engines and rate for 300HP continuous (and have several in service with over 5000 hours), that seems to be the best pick...and the 4L80E can stand over 250HP, based on the 6.5L's torque curve.

I may upgrade with the Phazar gear drive for the camshaft, as well.

In all seriousness, I bring up my trip through the engine rebuilder forest in case anyone with a 6.2/6.5L can benefit from it.

The all-new engine is on order from Peninsular Diesel:

230 HP, 18:1 pistons
New turbo (up to 12" boost)
New Stanadyne Injector pump, lines, and injectors
Phazer gear camshaft/injector pump drive
Mandrel-bent crossover

Should be here next week, or by 11/27.

Now I'll be able to pull a toad without overstressing the engine - or me.

quote:

Originally posted by Rusty:
The repair shop (genuine shade-tree mechanics - they do most of their work in the open) is going to dig a pit, tow the coach over it, and drop the engine straight down...

Won't they hit the "water table" after a foot or so?

Are you doing anything with the original transmission, torque converter, input shaft seal etc. while you have it out?

Have you priced another transmission or looked into the fea$ibility of an overdrive transmission?