Perkins 4-108 losing coolant

[BruceS]

I also had the same problem & it turned out to be the drain tap (faucet?) on the side of the block. Below the exhaust manifold. Use a mirror & torch to check it. Replaced it with a brass plug!

[KadeyKrogen38]

My guess is that with a Bowman heat exchanger the rubber caps are leaking coolant into raw water side. Only the pressure of the hose clamps stops this from happening.

[Greg Mason]

Wow, lots of great suggestions. When my 4-108 started losing coolant it didn't show anywhere either, but the reservoir kept getting dirty. My buddy looked and immediately said head gasket. It was leaking from exhaust into cooling, and a new one stopped it. No water in oil, no water in cylinder, no oil in water. Carbon in water.

[Thumbs Up]

I would pull and check the heat exchanger and if that looks okay look for a hole in the housing/manifold. There is a spot near the exhaust elbow that can pool a small amount of saltwater and corrode a hole between the coolant and saltwater. If it was leaking into the engine room you would smell it.

[dneve]

Thanks FionaJC for reminding me that Perkins engines are not sexist and are equal opportunity!
Lots of good recs to check out from all of you responders.
One old time Perkins person said try K & W block sealant sold online. He said it may work for small leaks and you must follow the instructions exactly.
Getting the Bowman heat exchanger/exhaust manifold off will be Bxtch! Very difficult to get to the manifold bolts.
Do auto parts stores sell the liquid to put in the coolant to detect exhaust intrusion?
Minor overflow from the coolant tank which was kind of dirty looking which could be caused by exhaust gas mixing with the coolant. No external leaks from the block. The water heater is connected to the coolant lines but no external leaks but will keep filling the coolant to hopefully find if there were air bubbles.
Will try the block sealant before tackling the heat exchanger removal.
Thanks for all your comments and will keep posting my findings. There are a lot of these Perkins still chugging away so long as we can keep solving these problems, they will keep running for many more years!

[thunderhoof]

I had a similar problem of coolant loss with no apparent leak on my 2002 Volvo Penta MD2030, also built by Perkins.
The result was not pretty.
I found first that the exhaust / raw water mixing elbow was severely blocked with hard but porous coke that barely allowed the engine to run. When I removed the elbow I found a similar condition on the manifold side of the exhaust port. I took the manifold to a radiator repair place to have it cleaned out. The next AM I got a call that there was a hole between the exhaust path and the coolant volume of the heat exchanger, right at the exhaust exit port. Clearly coolant was pouring into the wet exhaust path. Of course I could not detect the external leakage because it was being expelled in the overboard discharge. We tried to weld a patch in the area, but the damage was too extensive - so - new manifold for $1200US.
I fault the cast iron mixing elbow. Apparently they are known to fail / clog up after ~2000 hours. This results in a leak of raw water into the hot exhaust right at the manifold exit, not further down the path as designed. This causes the coke buildup, localized heating and manifold corrosion.
BTW, replace the mixing elbow with a stainless steel aftermarket item - cheaper than the Perkins part and should last much longer.

[dneve]

Thunderhoof"s situation sounds like my problem. I just replaced the exhaust elbow as it had developed an exhaust leak. I think there is a leak between the coolant and the exhaust allowing exhaust to enter into the coolant and coolant back into the exhaust. I just put the K & W block sealant in the coolant so I will see if that fixes the leak. If not then the manifold/heat exchanger must come off and hopefully the hole is repairable. If not Trans Atlantic sells the tank for $750. The engine runs very smooth so it is worth fixing. Will post if the sealant works.

[donradcliffe]

Its well worthwhile to used the Block Tester fluid kit

https://www.ebay.com/i/112219321782?chn=ps

before you start tearing down the engine.

I did work on a 4108 in Bali with the same symptoms where some of the heat exchanger tubes had failed. It was a model with a transverse Hx across the back of the engine, and I was able to replace the whole Hx it with a Chinese oil cooler for $50 and some creative plumbing.

You should be able to work the tube stack out of your Hx fairly easily and test the tubes for holes.

[dneve]

I actually bought a new tube stack from Orca Marine in Wash. thinking that was my problem but with the new tube stack in place, I was still losing coolant! I sent the old tube stack to Orca who checked it out and found no leaks. I now have an extra tube stack which I will sell on CF hopefully. I will be running the engine to see if the block sealant is working.

[theglo]

Originally Posted by dneve

Thunderhoof"s situation sounds like my problem. I just replaced the exhaust elbow as it had developed an exhaust leak. I think there is a leak between the coolant and the exhaust allowing exhaust to enter into the coolant and coolant back into the exhaust. I just put the K & W block sealant in the coolant so I will see if that fixes the leak. If not then the manifold/heat exchanger must come off and hopefully the hole is repairable. If not Trans Atlantic sells the tank for $750. The engine runs very smooth so it is worth fixing. Will post if the sealant works.

Hey! You have to love cruisers forum. Here I’ve been having a coolant leakage issue for 4 months and researched on here and found this thread; which is about my boat!! (Dneve’s old boat!)

Not to restart an old thread but I don’t think any of those fixes worked, lol!

The coolant still leaks, somewhere, likely out the exhaust. I have tried redoing to Bowman rubber end caps and adding an external coolant tank. I also think it’s the exhaust manifold.

By the way, Dick, if you read this, it didn’t leak too much for at least the first few hundred hours until we got to the DR.

I’ve put another 3 or 400 hundred hours on the engine since I discovered the coolant leakage problem. I’ve tried numerous fixes (see above plus other stuff) but the current method of choice is to keep 5 x 1 gallon jugs of coolant on board and top off 6 to 8 ounces each day before sailing.

We’ve made it from Florida to Antigua this way and May make it back as well.

BUT, I’d really love to solve the riddle. I’m hesitant to take the elbow off here as I’m only in one place for a week at most before moving on and don’t want to have to wait for parts.

Anyway, just saying thanks cruisersforum for the 5 year old thread about my own boat.

Justin

[theglo]

Originally Posted by dneve

Thanks FionaJC for reminding me that Perkins engines are not sexist and are equal opportunity!
Lots of good recs to check out from all of you responders.
One old time Perkins person said try K & W block sealant sold online. He said it may work for small leaks and you must follow the instructions exactly.
Getting the Bowman heat exchanger/exhaust manifold off will be Bxtch! Very difficult to get to the manifold bolts.
Do auto parts stores sell the liquid to put in the coolant to detect exhaust intrusion?
Minor overflow from the coolant tank which was kind of dirty looking which could be caused by exhaust gas mixing with the coolant. No external leaks from the block. The water heater is connected to the coolant lines but no external leaks but will keep filling the coolant to hopefully find if there were air bubbles.
Will try the block sealant before tackling the heat exchanger removal.
Thanks for all your comments and will keep posting my findings. There are a lot of these Perkins still chugging away so long as we can keep solving these problems, they will keep running for many more years!

Wait! You already replaced the exhaust elbow (albeit 5 years ago). When troubleshooting I put that old tube stack of yours back in there. Good to know ir tested well! But, man, if you already replaced the exhaust elbow I have no idea what else it could be.

[theglo]

Originally Posted by theglo

Wait! You already replaced the exhaust elbow (albeit 5 years ago). When troubleshooting I put that old tube stack of yours back in there. Good to know ir tested well! But, man, if you already replaced the exhaust elbow I have no idea what else it could be.

Clue if anyone is reading this years old thread. The coolant level seems to go down regardless of if I run the engine or not.