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Old 01-11-2012, 10:37   #1
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Working on an old Perkins 4.236



Bought a lovely fixer upper 43' steel Bruce Roberts Ketch with an old Perkins 4.236 this summer. Was running like a top. Operative word is 'was'.
To make a long story slightly shorter, when we bought her, we had 2 weeks to get her in the water, and back to our home marina, so a lot of what should have been done before launch was not. My fault entirely. Bottom line is that the first day out I overheated her, and had to limp back to the marina. In the process we split the rubber muffler on the wet exhaust. Probably a combination of a 20+ year old exhaust, and the overheating.
After changing the thermostat, topping up the coolant, and a stop gap repair on the muffler, off we went again. This time, before we even got out of the marina, the hydraulic transmission wouldn't fully engage in forward. Never got more than a knot or 2 out of her before the tranny started overheating. Now I knew we were beat, and I just had her towed to our marina where she has been sitting since the end of July.
Since then, I exchanged the blown out rubber muffler with a plastic one and started her up twice. Once I ran her on and off for about an hour to see if the transmission problem could possibly be just an airlock. There was no pressure guage on the transmission, so I put one on. Sure enough she would drive in forward for a few seconds then I'd loose pressure and poof, no drive forward. I spent the next half an hour running it in forward and reverse, checking the tranny fluid, and when it didn't seem to be getting much better I shut her down, and called it a day. The transmission fluid smelled burnt, so I left it with the intention of replacing the tranny fluid, and giving her another shot in the hopes that this would solve the problem. I know, not likely but it was the cheapest, easiest solution short of pulling the tranny out and getting it rebuilt. (probably where I am going unless someone has another suggestion)
Ok, where was I...
Ah yes, since that day, I hadn't run the engine. Then about a month ago, in preparation of haul out, I went to start up the engine, and she laboured quite a bit before catching. When she did, I ran her for maybe 1 to 2 minutes, and something didn't sound right. I shut her down, and went below. The starter solenoid was clicking madly, and I could smell burnt wiring. I disconnected the battery, and upon inspection I found that the signal wire for the starter was pinched between the positive battery lead and the wood frame around the engine enclosure. End product was that for the 2 minutes that I ran the motor, the starter was engaging. Result: cooked starter.
Now, I replaced the starter, and was going to give her another shot, and checked the oil as part of my prestart, and voila! Caffee Mocha oil! First thought, blown head gasket! I started to drain the oil, and 2 litres of pure clear water before I got a drop of oil.
So, how do I get water in the oil??? Blown head gasket would mean coolant, not water in the oil. Raw water pump seal was number 2. Nope, no physical way since if the seal on the raw water pump was blown, the water would end up pi$$ing out of the shaft seal into the bilge, not into the motor. Third through the heat exchanger. Nope, coolent is between the exhaust manifold, and the raw water heat exchanger. Again, I'd have coolent not water in the oil.
The only thing left, is that water is somehow backing up the wet exhaust into the engine through the exhaust port? Does this sound feasible?
I disconnected the muffler, and of course I got raw water in the bilge from the full exhaust, but even after 'Sandy' I didn't get any water coming in the bilge through the exhaust pipe from outside.
Now I'm in a quandary. Old boat circa 1970 Perkie 4.236 been flooded with water. (Oil has been changed, but not yet run.) I've pulled the injectors and was advised to crank the engine with the injectors out, (and of course fuel off) to drive any remaining water out of the cylinders, but before I do, I need to deal with my exhaust issue. Since the only thing I've done to the exhaust is replace the muffler with a plastic one, I figure that must be the problem. I've looked online for anything that even remotely looks like muffler that was on it, and can't find anything. I've attached pics of the original rubber muffler, and the tie in where the raw water connects to the exhaust. I figure its GOT to be the plastic muffler I put on screwing with the flow of water/exhaust to the point that water is backing into the exhaust ports. I have no idea what to do, or what to replace my antique muffler with. Any suggestions would be appreciated.
Oh, by the way... Haul out this year has been cancelled due to low water level in Lake Ontario. She is presently laid up afloat. Boat, 6ft draft, channel 4ft deep.
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Old 01-11-2012, 11:03   #2
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Re: Working on an old Perkins 4.236

Hmm... surprised you havent checked the rubber impellor? It could have been the original problem of overheating.... especially after sitting a long time. When these go bad on a 4-236... the chunks go into the transmission cooler. If you ran the starter a long time without it starting up, you may have put raw water in the exhaust until it went into the engine. That muffler appears awful small, the muffler on mine was probably about 3-4 gallons capacity. Is there an oil cooler on your engine? I suppose the raw water could get through there into your oil. Those are great engines, hope you get yours sorted out.
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Old 01-11-2012, 11:12   #3
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Re: Working on an old Perkins 4.236

When you turn the engine over with the injectors out, make sure to put an old beach towel or blanket over the engine or anything in it will paint your engine room walls. You can guess how I learned that one. Might as well do a compression check while you have the injectore out. If they are fine then that is one less thing to worry about. If the compressions are not good, dont panic. Letting the engine sit can, and often does give low readings. After it has been run for a while re-check and most likely the readings will have come up. What type of transmission do you have? I am sure you will get lots of advice here.____Grant.
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Old 01-11-2012, 11:38   #4
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Re: Working on an old Perkins 4.236

We had to have a special adaptor machined to check the compression on mine. I paid half and my mechanic paid the other half. Not sure why you cant use a hand help compression gauge... inaccurate?
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Old 01-11-2012, 12:58   #5
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Re: Working on an old Perkins 4.236

Does the transmission have a separate cooling line or is it part of the engine cooling system? Just curious if there is some connection between trans and engine that could let water in via the transcooler?

kind regards,
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Old 01-11-2012, 13:38   #6
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Re: Working on an old Perkins 4.236

Hand held compression guages usually dont read anywhere near high enough for a diesel, and the rubber sealing cone is much too small for the larger opening that an injector uses. What I did was to get an old injector body (no innards) and had a plate welded over the top, and then drilled it for the thread of a diesel rated guage. I think it read up to 900lbs. You dont find those high pressure guages at the regular automotive stores, but I am sure an internet search will locate one. I hope this helps.____Grant.
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Old 01-11-2012, 15:12   #7
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Re: Working on an old Perkins 4.236

The 4236 on our boat is cooled by keel coolers and the exhaust goes up a funnel but the PRM transmission is cooled from an exchanger built into the system. I'm thinking about your heat exchanger/s, if they have been allowed to corrode too much internally then you can get a drop of pressure/volume of coolant in the engine as the water pump would pump coolant out under pressure but not suck any water back, so levels would be horrendously low.

Water and/or coolant in the oil, short of condensation, always has to be a fault within the engine somewhere.

Seems to me that you're suffering from the usual, and painful, malady of buying a "little used" boat . . . you simply never know what will go wrong next.

Sorry.
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Old 01-11-2012, 22:37   #8
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Re: Working on an old Perkins 4.236

Quote:
Originally Posted by Cheechako View Post
Hmm... surprised you havent checked the rubber impellor? It could have been the original problem of overheating.... especially after sitting a long time. When these go bad on a 4-236... the chunks go into the transmission cooler. If you ran the starter a long time without it starting up, you may have put raw water in the exhaust until it went into the engine. That muffler appears awful small, the muffler on mine was probably about 3-4 gallons capacity. Is there an oil cooler on your engine? I suppose the raw water could get through there into your oil. Those are great engines, hope you get yours sorted out.
Thanks for the input. Actually I checked the raw water impeller when I limped her back in the first time after it overheated. It's fine, and plenty of water coming out of the exhaust when it was running.
Good pick with the oil cooler. I thought of that too, but sorry, no oil cooler on this old girl
I agree the muffler looks small, but it has been the one used since 1990 when she was first commissioned, so even if it was too small, it must have been at least adequate. (but maybe less than ideal?)
Thinking in this vein, the muffler I replaced this with has a slightly smaller inlet size 2" instead of 2 1/4", but more internal volume. The old one is basically a straight flowthrough with a rubber flapper on the outlet. The one I replaced it with has at least 3 or 4 returns so in retrospect, I'm sure it does build more back pressure. At the time, I replaced it with the one I did just because it fit.
I could use some more info on what is a proper size modern (available) muffler and wet exhaust. Nothing I've read gives me anything definitive.
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Old 01-11-2012, 22:47   #9
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Re: Working on an old Perkins 4.236

If your engine is below the water line it should have a vented loop. My brother found this out the hard way......twice.
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Old 01-11-2012, 22:55   #10
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Re: Working on an old Perkins 4.236

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Originally Posted by gjordan View Post
When you turn the engine over with the injectors out, make sure to put an old beach towel or blanket over the engine or anything in it will paint your engine room walls. You can guess how I learned that one. Might as well do a compression check while you have the injectore out. If they are fine then that is one less thing to worry about. If the compressions are not good, dont panic. Letting the engine sit can, and often does give low readings. After it has been run for a while re-check and most likely the readings will have come up. What type of transmission do you have? I am sure you will get lots of advice here.____Grant.
Hey Grant. Thanks for the advice
The plate on the tranny is almost totally obliterated, so any model number, or serial number is long gone. I did do a pencil rubbing and its a Paragon Hydraulic Reverse Gear transmission. After a load of research, I 'think' it is a HF7 but this conclusion is just from finding pictures on the net, and comparing it to pictures of mine. If it isn't an HF7, its very close.

Feeling more like a detective than a sailor right now
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Old 01-11-2012, 23:02   #11
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Re: Working on an old Perkins 4.236

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Originally Posted by SkiprJohn View Post
Does the transmission have a separate cooling line or is it part of the engine cooling system? Just curious if there is some connection between trans and engine that could let water in via the transcooler?

kind regards,
I don't think so.
Raw water goes from the raw water pump, to the heat exchanger on the manifold, raw water outlet from the heat exchanger piped into the transmission cooler, then out of the transmission cooler to the dry downpipe from the engine exhaust. See the pic on the original post. The red hose goes to the blue transmission cooler, and you can see the outlet from the transmission cooler where it mixes with the exhaust.
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Old 01-11-2012, 23:06   #12
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Re: Working on an old Perkins 4.236

I could not tell if you actually replaced the impeller. If not I suggest that you do replace it.

The impeller on my 4.236 looked OK from the outside and had good water flow and held temp at all loads but when pulled it had a number of nicks and missing pieces to the vanes that did not show with side inspection. (Chase those pieces down and pull them out).

With a new impeller the water flow increased by 20% or 30% giving a much greater latitude for thermal considerations.

REgards

I should add that my engine has a raw water - coolant heat exchanger, an engine oil cooler and a transmission oil cooler all cooled by the raw water circuit. The engine and transmission oil coolers are part of a single dual heat exchanger system.
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Old 01-11-2012, 23:11   #13
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Re: Working on an old Perkins 4.236

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Originally Posted by perchance View Post
If your engine is below the water line it should have a vented loop. My brother found this out the hard way......twice.
Hi, the waterline is at least 3/4 up the engine, so I guess officially it is below the waterline. Nope, no vented loop. Where are you talking about? At the exhaust, or on the raw water inlet? Please enlighten me
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Old 01-11-2012, 23:15   #14
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Re: Working on an old Perkins 4.236

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I could not tell if you actually replaced the impeller. If not I suggest that you do replace it.

The impeller on my 4.236 looked OK from the outside and had good water flow and held temp at all loads but when pulled it had a number of nicks and missing pieces to the vanes that did not show with side inspection. (Chase those pieces down and pull them out).

With a new impeller the water flow increased by 20% or 30% giving a much greater latitude for thermal considerations.

REgards

I should add that my engine has a raw water - coolant heat exchanger, an engine oil cooler and a transmission oil cooler all cooled by the raw water circuit. The engine and transmission oil coolers are part of a single dual heat exchanger system.
I'll definitely take your advice and replace it. Actually I've got 2 on order
I removed the heat exchanger tubes from the manifold, and other than some very minor scaling, all the tubes are free and clear.
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Old 01-11-2012, 23:17   #15
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Re: Working on an old Perkins 4.236

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Originally Posted by Rob Toronto View Post
Hi, the waterline is at least 3/4 up the engine, so I guess officially it is below the waterline. Nope, no vented loop. Where are you talking about? At the exhaust, or on the raw water inlet? Please enlighten me
I'm not sure as the boat is in Vancouver but will ask next time I talk to him. He said the vented loop fixed the problem. I suspect it is in the raw water inlet.
P.S. you can get the manual for your transmission online.
If you lose reverse or it slips there is an adjustment on the side of the tranny to adjust the reverse band. Simple to do if you need to.
Anthony Keats in Port Dover (I think that's where he is) has parts for the Paragons.
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