The Boating Forum - cat 3208 loosing coolant

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View Full Version : cat 3208 loosing coolant

07-27-2007, 05:55 PM
I loose about 1/2 gallon every trip. I've run the engine and looked for leaks around hoses and such. It definatelty isn't the heat exchanger. I'm not getting water in my oil. It seems like it is a cracked manifold or manifold end cap gasket.
The question is how can I tell without hauling my engine ( not much room).
Any ideas??

07-27-2007, 06:13 PM
Possibly the twist-on cap itself is allowing some to escape. It will steam off of the engine before you notice a leak. I have been dealing with a similar problem on one of the MAR-T's 3208s. We pulled the heat exchangers and had them rodded. Nothing was found so far as pin holes or blockages.

After getting the heat exchangers back, the port side cap would get blown off sometime during the trip. I'd generally smell antifreeze and head downstairs and refill the exhanger and put the cap back on. After a little investigation, I found that the filler neck on the exchanger, where the cap snugs down, had been slightly bent, not allowing a good fit for the cap. A little rebending of the neck with a screw driver and things are better. Note, I did not say completley right. First trip out after my handi work and I smelled that familiar roasting antifreeze odor. To my surprise, the cap was still in place. However, the heat exchanger was pushing out water/antifreeze into the small over flow container and spilling into the bilge. Nothing much I could do. The temp gauge read that we were OK on temp, around 190. I let it cool overnight and checked the fluid level in the heat exchanger and it is full, and so is the overflow container. She's run about a half dozen trips like that since with no change.

I am just going to hide and watch and see if anything changes.

CB Haws
07-27-2007, 07:51 PM
Could be the famous Cat 3208 headgasket starting to let go. Keep an I eye on it. I am in the process for putting my heads back on after a cylinder to cylinder leak. Engine sounded like a popcorn machine. Last fall the starboard one was just starting to leak water out the exhaust. Lost a couple of quarts each trip. Pulled the head and sure enough #5 was just starting.

07-27-2007, 08:04 PM
Head gasket or head itself. Get it fixed now or pay the piper later.

07-27-2007, 08:29 PM
Pressure test the system with a pressure tester andlook for leaks. If it isnt dripping out, it is going inside somewhere, pop off the heads...

07-27-2007, 08:55 PM
Got the same problem with my port engine.
Blew a coolant hose clamp last year, nearly cooked the motor (in case you didn't know, no coolant will NOT trigger an overheat alarm!).
My mechanics pressure checked the coolant system, checked for contamination in the oil, no saltwater in the coolant, no significant steam in the exhaust.
I agree that it's got to be going somewhere, doesn't it? But is a small amount of coolant loss such as this (1/2 gallon in a system that holds, I think, around 20 gals) absolute proof of a leaking head gasket? My mechanic said that if it were a head gasket the symptoms would be obvious- like water blowing out the recovery tank.
Pulling the heads on a 3208TA can't be a cakewalk and I'm sure would be quite expensive so I'd need to be SURE that's the problem.

Let us know how it goes.

07-27-2007, 11:44 PM
I think the gasket is more likely, but you could try upgrading to the 13 Lb pressure caps from the standard 7 Lb ones.

07-28-2007, 02:47 AM
Thanks for all the advise, I'll update you all.............

CB Haws
07-28-2007, 07:31 PM
Talk about a PITA. I just love the comment pop the heads off. That my friend is bull$hit in it's purest form. Let's see. to pop the heads off you have to remove all the injector lines, air intake system, lots of linkage and brackets, valve covers, rocker arms, injectors, pushrods, manifolds. Oh you need to drain all the coolent, and change the oil after the job. All the head bolts. Then pull off the heads they only weigh a 150 pounds a piece. Then you need to spend a day cleaning all the gasket mating surfaces, cleaning the heads, injectors, every nut and bolt, need to run out for new hoses, ect. Now you can start the process of putting the heads back on after you spend $400-500 bucks for a gasket set. Torque the heads in a four step process ending up at 120 pounds. Then you reinstall the injectors after you take the to get new seals pressed on. Oh now set the valve back lash. Put everything back together and fire her up. Shut her down pull the valve covers again and check the back lash. Yea I am going to run right out and pop my heads.

Butch Davis
07-28-2007, 08:42 PM
Does the engine have an intercooler? I've seen CAT's leak coolant from the intercooler into the intake air. A slow leak won't show much smoke, if any. One test is to remove the HX pressure cap and watch for bubbles. I've heard that intercoolers can be an issue on CATs.

07-28-2007, 10:14 PM
Don't rule out the exchanger! A number of years ago I was pulling my hair out over a 355 hp 3208 that would hold 20 psi on the cooling system all day. Take it out and run it up to temp and in 40 min it would loose 2 gallons. I had the tube bundle press tested at the radiator shop twice and I was assured it was fine. After testing everything else and thinking the worst, I swapped bundles and ran it. The problem moved to the other engine. Ordered a new bundle and problem solved.

07-29-2007, 08:30 AM
Under the expansion tank is a small elbow 3/4 inch hose had this loosen up on me . Very hard to see need strong flashlight. There is no need to remove whole assembly of expansion tank to clean. Remove end caps . You willneed a threaded rod { home depot ] 3ft or so long , you can then clean each honeycomb pushing the rod from inboard to outboard then hose. Twenty two years of 3208 maintenance you find some short cuts. Do you have a pressure tester to attache to expansion tank?Not too enpensive or rent this will greatly reduce looking for leak. Hope this helps Stephen

07-29-2007, 05:41 PM
Do not pop the heads off! The 3208 series probably has the strongest head/gasket/block setup of any motor, you really have to do something stupid to have a head gasket let go. More then likely your culprit is going to be the exhaust manifolds, crossover tube or the elbows at the end of the manifolds. I had the exact same problem, the motor ran great, but I'd have to fill up the coolant every couple of hours. The way we found it was by putting dye into the coolant (lots) and letting the engine run at the dock, sure enough after about 20 minutes you could see the dye coming out of the exhaust...

If indeed the manifolds are the cause of your problems, have a good strong drink before you get pricing from Cat, luckily there are VERY good aftermarket manifolds available.

07-29-2007, 08:37 PM
Mine did the same thing. I purchased a Stant pressure tester and pressurized the system. Every lead became easily identifiable. All my leaks were either on the front of the engine or at hoses where the hose clamps needed tightening. I went from adding 1-2 gallons per engine per trip to a few ounces total after finding all the leaks.

Can't recommend the pressure tester strongly enough. It is a great tool.

CB Haws
07-29-2007, 09:28 PM
Hey MEK so just who sells these aftermarket cat manifolds? Strongest headgasket another pure bull$hit statement. Cat went to stronger bolts and therefore higher torque. What they really needed to do was go to a bigger bolt. 3208's have very little room between intake and exhaust valves. So cracks are another problem. When you are making truck motors who cares; but boats put the pressure on. Pressure testing will help locate hose and some gasket leaks; but I have seen 3208's hold 15 pounds for days. Heat them up and they leak. When I was running down my first headgasket leak I pumped the pressure up to 20 psi. It would hold pressure overnight. What I finally did was take her for a run. The next morning I pulled the elbows. I could just see a little wetness in the manifold. When we pulled the head number 5 was just starting to leak. Don't get me wrong I love my Cats. They are easy to work on and parts are not sky high like yanmars or vulvas.

07-29-2007, 10:40 PM
CB Haws - 7/29/2007 8:28 PM

Hey MEK so just who sells these aftermarket cat manifolds? Strongest headgasket another pure bull$hit statement.

No need to over react. To each his own, I can only speak to my experience with overheating 3208s. I had one experience where I unknowingly overheated one motor to the point where the manifolds were RED hot. I thought the heads and head gaskets were toast, my mechanic checked the motor out, found nothing wrong with the heads or gaskets, put on new manifolds and I'm still good 4 years later. Perhaps we need to take into account the age of the motors in question, my motors had under 500 hours when they were overheated, maybe an older higher time motor would have had the gaskets go.

I still think that if you don't see any visible leaks or find coolant in your bilge, I would check the manifolds before "popping the heads off".

07-29-2007, 11:11 PM
CB, agree with the statement about not being able to find head gasket leaks by pressure testing. I should have said to pressure test the system to rule in or out any serious problems. Fix all leaks you do find while pressure testing.

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