Logo
Click for Chrysler parts and manuals!
Results 1 to 5 of 5
  1. #1

    Default Chrysler 318 raw water cooling duel impellor sherwood pump

    I think I have finally got this sorted anyone who like me has searched the internet for details of the duel impellor set up will know there is little info out there and much conflicting info.
    I have a mid seventy's 318 marine motor and it is fitted with an alloy eddlebrok 2176 intake. first issue is the front water passage on the 2176 intake is straight across connecting the head ports, I overcame this by fitting an alloy baffle plate beside the thermostat aperture effectively making 2 separate chambers , also to help overcome corrosion I epoxy painted the interior faces of the water passages. the raw water route that appears to be working now for me as follows;
    thru hull intake piped to rear pump connector - rear pump exit port splits to 2 smaller hoses that connect to exhaust manifolds at the top front end then water flows through the exhaust jacket (distribution pipes correctly fitted) and out of the manifolds at the rear into the top of the transmission oil cooler- the water then runs to front pump intake port and into the cast water crossover device and into the starboard block- back through the head and into the 1st camber of the intake not the one with the stat in, - then out of the intake by way of a u hose into the other crossover passage -then in to the port block- head and out to the thermostat chamber of the intake manifold water passage, the water is pretty much up to temp straight away then stat opens and water runs to exhaust elbows and overboard, there is a smaller out put bypass to the thermostat top hat housing that sends a constant stream of water to the exhaust manifolds to cool them, this flows through the manifolds from the front lower inlet to the rear outlet that fills the tranny cooler and joins the loop etc.
    I ran the boat which is 1956 Chris craft Capri 21' last Sunday, it ran good, temp gauge was constant 180deg. f with little fluctuation gauge may not be accurate, manifolds were warm to touch about 120, block was even temp good flow out of exhaust .
    this system is renown for misinterpretation ,incorrect fitting and variation, later it appears that Chrysler issued a service bulletin that did away with the duel impellor system, at present I have decided to stick with it, does anybody have any further advice or comments to add to this topic, It seems to me for example that the starboard block is cooled before the port block with pre warmed water which when it enters the port block must be at a higher temp sounds a bit mad to me, also I have seen the raw water routed direct to the tranny cooler without going through the exhausts, and some guys don't fit the distribution tubes at all ?
    I would like to complete the information trail on this to try and save others the long slog of trying to search out the facts, this was particularly difficult for me being in England and there not being any boats to go have a look at.
    thanks for all your advice
    David
    David
    York England

  2. #2

    Default Re: Chrysler 318 raw water cooling duel impellor sherwood pump

    Have you any nice photos to share?

  3. #3
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    9,092

    Default Re: Chrysler 318 raw water cooling duel impellor sherwood pump

    David,

    I would have done what's necessary to rid myself of the dual pocket seawater pump system, and make the changes so that I could use a single pocket seawater pump. We will find more RWC Marine Engines using a single impeller seawater pump than we will RWC Marine Engines using the old outdated dual pocket pump systems.

    FYI and FWIW..... epoxy paint or not..... you will be at risk of the Automotive aluminum intake manifold living a rather short life in a Marine Raw Water Cooled engine environment.
    The dissimilar metals, along with the incorrect PH balance of river/lake/ocean water, will create galvanic corrosion.
    The epoxy paint may help for a while...... but ultimately corrosion will win.

    What is/was the issue with the "front water passage on the 2176 intake"?
    This passage is a coolant cross-over, and is necessary to allow the coolant (seawater if RWC) to exit the engine and enter the exhaust system!


    All that having been said...... if your system now works, that is great!


    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  4. #4

    Default Re: Chrysler 318 raw water cooling duel impellor sherwood pump

    What is/was the issue with the "front water passage on the 2176 intake"?
    This passage is a coolant cross-over, and is necessary to allow the coolant (seawater if RWC) to exit the engine and enter the exhaust system!

    The dual impeller system routes the RW to the right bank and then to the left bank, the front passage is blocked off, the threaded hole larger, and the thermostat relocated nearer the thermostat. The crossover is the oddball front casting. Very proprietary to earlier A and LA engines. People love to go "original", there must be some stories out there of attempts to use that original manifold on an automotive application.

  5. #5

    Default Re: Chrysler 318 raw water cooling duel impellor sherwood pump

    Quote Originally Posted by mcomm View Post
    What is/was the issue with the "front water passage on the 2176 intake"?
    This passage is a coolant cross-over, and is necessary to allow the coolant (seawater if RWC) to exit the engine and enter the exhaust system!

    The dual impeller system routes the RW to the right bank and then to the left bank, the front passage is blocked off, the threaded hole larger, and the thermostat relocated nearer the thermostat. The crossover is the oddball front casting. Very proprietary to earlier A and LA engines. People love to go "original", there must be some stories out there of attempts to use that original manifold on an automotive application.
    Yes as I understand it that correct seems mad to me that you can have different cooling temps in each bank of cylinders maybe that is why Chrysler stopped doing it this way, however there seems to be plenty of examples out there especially in the correct craft range. also Osco state that you should fill the manifolds low end to high to avoid trapped air, mine don't and never have but the previous installer could have got it wrong?? the alloy 2176 inlet adaption was pretty simple I opened up the top port to 3/4 spigot tail and was able to get my fingers in to hold the baffle plate in position after inserting it through the stat hole then with Plasticine held it in position whilst pouring high temp epoxy in from the other side when set turned it over and repeat from the other side seemed to work well and did not need spe******t welding by a gynecologist!! interestingly I did run last year on Loch Lomond in Scotland with the eddlebrock fitted as standard not modified into 2 separate chambers and it blew out the port head gasket in a big way, conclusion was there was two opposite flows of cooling water in the head and they boiled when they met in the middle of the head, could have been anywhere in the circuit but it blew the head lesson learnt !!!
    will try topost pics but have failed twice now
    thanks for your interest David, York, England
    David
    York England

Similar Threads

  1. What water pump impellor repair kit do I need?
    By Beagleman in forum Mercury Mariner Outboard Forum
    Replies: 5
    Last Post: 07-27-2013, 06:58 PM
  2. How to get to the impellor/water pump.
    By deano3433 in forum Suzuki Outboard Forum
    Replies: 2
    Last Post: 03-03-2013, 05:53 AM
  3. '71 318 cooling probs with duel imp pump
    By limige in forum Chrysler Inboard and Sterndrive Forum
    Replies: 3
    Last Post: 06-01-2010, 01:03 PM
  4. Water pump pulley removal 318 chrysler sherwood pumps
    By mciron9 in forum Chrysler Inboard and Sterndrive Forum
    Replies: 12
    Last Post: 05-26-2009, 04:04 PM
  5. Chrysler 318 cooling problem Sherwood D60
    By beanstalk in forum Chrysler Inboard and Sterndrive Archive
    Replies: 3
    Last Post: 12-28-2008, 04:55 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •