1974 455 Oldsmobile jetboat engine

Jet boat leak

Sorry guys should have read the comments ahead before I posted. Found the answer. Thanks!

 

Exhaust manifolds Stainless Steel

I can supply stainless log style one piece manifolds (complete with exhaust outlet - not flange, 3" or greater) or high performance riser type watercooled manifolds which will not allow water reversion. check with www.victorianmarinetechnology.com.au for more details. Julius

 

Julius
I had a look at your web site--Nice manifolds there, Whos the drummer? Jeesus had to dive for the volume button.
I was looking for but did not see any thing on the Yanmar 6Lp exhaust elbow mixer --as they call it. I have nothing wrong with them at the moment but Yanmar suggest replacement at yearly intervals. Well they would wouldnt they. However I shall replace them one day I suppose and when I do I want to use a high rise from the turbo and then I can use a staight exhaust right out the back. Its only a 4 inch 90 degree pipe with a water mixing fitting. Easilly fit one in a shoe box
Got anything on that?

 

I believe we have made these before. We make elbows for quite a few turbo diesels (this seems to be the main part of turbo diesel exhaust failures). If you go back to the website and send an email with Jpg of elbow next to a ruler for scale, I can confirm and quote.

 

I bought a 77 Taylor SS with a olds 455, I bought it knowing it was getting water in the oil. I assumed a head gasket, but as I got in to it i found the olds has a large steel valley pan. Instead of having a rubber or cork gasket the pan was the gasket but with a black RTV sealant. My engine only had 110 hours on it since rebuild. Although it wasn't taking water after I replaced the head gaskets and up my engine only lasted a few more hours I think even though it was a very small amount of water getting through the damage was already done. I through a bearing and I'm now waiting for tax returns I have asked around, Alot of people have told me exhast manifolds (water jackets) but that doesn't make much sense. The only problem i saw was with the original intake manifold has holes in the rear for the heater lines, which have been plugged because heat is not necessary. I think the plugged heater lines might be preventing proper coolant flow and be creating hot spots...... Thats my opinion but I'm not sure I'm just your average shade tree mechanic!

 

455 olds

Hi, I can help with watercooled headers for your Olds. email info@victorianmarinetechnology.com.au for tech FAQ

 

I had a GMC gas system that defied explaining why I had water in the crank case.

All that it may have been is that the engine cannot exhaust the condensation generated and it settles into the pan when the engine is shut down. This suggests a restricted breathing vent.




Ray

 

jet boat 455

i am haveing same thing going on with my olds 455 in my 76 jet boat.
new motor, first weekend out, an hour and 20 min into it started to see oily water in the back of the boat. i imediatly pulled dipstick and saw water in the oil. first thing that came to mind was too much pressure because of researching the problem. i talked to a guy at jet boat performance and he said that it shouldn't be doing that. in my experiance with olds motors in an automotive stand point i have found that this is a common problem and am assuming that its the same with my boat motor. i am hopeing that the pressure release valve will correct this. i am getting ready to pull motor and change my intake gasket(mr. gasket gasket kit) and flush the motor and put a ball valve in line with a water pressure gauge. if any one has had this problem before and corrected it with the said valve, can you let me know how the results turned out?

 

OK, I'm new here so bear with me, but looks like I've got the same problem. Jet boat with a 455 Olds and it ended up with alot of water in the oil. I had run this thing with the same engine for at least 5 years with no problem. Before taking it out a few days ago I happened to check the oil and it was all frothy with water in it. Since the boat sets outside I thought maybe rain had just leaked into the engine so I changed the oil and took it out the next morning. I didn't make it over 5 minutes before I ran into trouble. The oil pressure dropped off and the engine began to dog down. I shut it off before it locked up completely. Now I'm back with the water in the oil again. I have pulled off the heads and don't see any evidence of a blown head gasket. But just running for about 5 minutes with THAT much water in the oil I'm thinking it has to be a pretty good size leak. I haven't made it into the crankcase yet.

 

74 olds water in oil

ive got it!! i installed a water pressure gauge on my water inlet from my jet pump... 85lbs at 4000rpm. Thats crazy, i called berkeley they told me that is normal for the jet pump but olds motors leak behind the timing chain cover with this much pressure. They gave me 2 options a (gate valve) NOT a ballvalve or they sell a pressure blowoff for about $80 i tried the gate valve and had no problems till i really started opening her up... holding 5000 rpm. im goining with the blowoff valve in the spring!!

 

Where did you get your blow off setup and how did you install it.

 

Couldn't you just use some type of water pressure regulator? I've seen a few of them on eBay for under $50.00.

 

455

Well I called Mondelo out of califonia and they said to use a ball valve set up of hoses for water to exit of the back of the intake. i was told to leave valve wide open. this set up worked all summer untill the last 2 trips i started to notice water again. I changed all of the gaskets after i put valve on, and it is quite possible the water could be comming out of the timeing chain cover even though they said it usualy comes out of the water jackets on the intake. back to square one will try a diffrent set up to see if i can figure out.

 

The fix to your problem

Hello all, I have a 1970 Eliminator with a Berkley 12j pump. Although there are several good ideas given in the above replies, I'm a master machinist with lots of Olds experience. As someone previously stated the problem with the cooling system is a pressure problem. Although it is possible to lower the pressure by installing a valve on the water inlet side of the motor, it is not the best course of action. The olds water pressure should not exceed 20psi Max. on my system my pump puts out a staggering 210 psi of water pressure. I had the same problems as listed with milky oil and excess water in my oil pan the simple fix is installing a pressure regulator valve. It is almost like a thermostat but operates by pressure only and not temperature. Install one on your water inlet side of the cooling sytem and your problem will be solved. This is an Olds only problem. The high pressures are causing gasket failure at the intake manifold usually and at times the head gaskets. I would install new head gaskets, and a new intake manifold gasket. Also use a metal valley pan intake gasket with plenty of sealent on it. The Olds big blocks are prone to leaking intake manifolds if you don't silicon the hell out of them. Happy Boating. Oh jetboatperformance.com sells the regulators they run about $40.00

 

fresh water cooling kit 455 olds

Does anyone know if the older big block 454 heat exchangers will work on a typical 455 Olds block? I'm interested in a raw-water cooled 454 jet boat but need to convert for use in salt water. Berkely 12jc if it matters.

Any thoughts appreciated.