Return to the home page...

Go Back   Moyer Marine Atomic 4 Community - Home of the Afourians > Discussion Topics > Cooling System

Reply
 
Thread Tools Display Modes
  #1   IP: 38.118.52.41
Old 11-14-2005, 09:19 AM
Unregistered
Guest
 
Posts: n/a
Question Engine temperature down

My late model Atomic 4 was acid flushed earlier in the season per your book. The engine ran fine and was cool. After a month or so the engine temp went up. I recently added the restrictor valve and changed the plugs. When I ran the engine the temp was down considerably (around 120). As I inspected the engine, I found what appeared to be water bubbling around spark plug #3 with a white powder forming around the base of the plug. There also appeared to be steam coming from the exhaust that had not happened before. This engine is raw water cooled and has what appears to be plenty of water flow out the exhaust. Any ideas?
Reply With Quote
  #2   IP: 38.118.52.41
Old 11-14-2005, 09:22 AM
Don Moyer's Avatar
Don Moyer Don Moyer is offline
 
Join Date: Oct 2004
Posts: 2,811
Thanks: 0
Thanked 183 Times in 124 Posts
The elevated temperature which was quickly remediated by a restriction in your bypass loop was probably nothing more than a bit of crud becoming lodged in the "T" fitting in the middle of your water jacket side plate. The fact that you still have plenty of water flow out of the exhaust indicates that the pump is working fine and that there is no unusual restriction in the cooling passages. Otherwise, your total flow would be reduced out of the back of the boat after you installed the restrictor valve.

Water collecting around the base of a plug usually comes from a small leak from one of the studs that seeps back on the top of the head until reaching one of the recessed areas around a plug. The white deposit is from the minerals (possibly salt) that precipitates out of the water.

Steam from the exhaust, in an engine that has plenty of water flow out of the exhaust, is frequently an indication of a small crack in the manifold or (worse) one of the exhaust ports in the block. Steam also frequently generates within the exhaust system itself when precipitate builds up where water is introduced into the hot section.

I would do a couple of things in the following sequence to address each of your three symptoms:

1) Remove the hoses from the front and rear of the manifold and then pressurize the manifold by holding a finger over one end while blowing into the other end. You may have to blow quite hard to find a very small crack, but in most cases a leaky manifold will be found quite easily by this simple method. If the manifold leaks, it will need to be replaced.

2) If the manifold checks OK, reinstall the hoses and squeeze the hose from the rear of the manifold to restrict the flow of water while running the engine. The added pressure within the cooling jackets of the engine should enable you to discover where the leak is located that is finding its way to the recessed area around the third plug. Small cracks on top of the head can usually be sealed using one of the small fiber glass repair kits from West Marine. If water is seen to be seeping up through one of the studs, the stud will need to be removed and resealed.

3) Remove the hot section of the exhaust (between the back of the manifold and the inlet to the water lift muffler) and inspect for a large build up of crud where the water enters the hot section.

4) If there is no restriction within the hot section to explain the steam, remove the manifold and inspect the exhaust and intake ports in the side of block. Look especially closely at the exhaust ports (one at each end and two in the center of the block). If there is a leak in one of the exhaust ports there will usually be rusty discoloration in evidence.

5) If no other source of the steam from the exhaust is found (manifold OK, hot section of the exhaust unclogged, and no obvious signs of water from any of the exhaust ports), I would do a simple pressure check of the block and head.

The easiest way to pressure test the block (without removing the head) is to first plug the outlet of the thermostat housing. Then remove the hose from the outlet of the water pump, and install a hose barb, a threaded coupling, and a Shroeder valve in the end of the hose, so that a standard bicycle tire pump with a built in pressure gauge can be used for the test. A Shroeder valve is the standard valve used on automobiles, and they are available at any auto parts store. If no bicycle tire pump is available with a pressure gauge, you can install a "T" fitting ahead of the Shroeder valve to accommodate a pressure gauge. The block should be able to hold 20 psi for an hour or more without a noticeable drop in pressure.

NOTE 1: It would be preferable to remove the manifold for the above pressure test so that the valve ports can be inspected during the test. If, in removing the manifold, one or more studs unthread from the block, you will have to reinstall the studs to prevent air from leaking out of the cooling jacket during the test.

NOTE 2: In many cases, it is preferable to drain the water out of the block and head for the test and listen for an air leak. Small leaks in a combustion chamber (particularly the combustion chamber of the head) can usually be heard through the spark plug hole.

If pressure decays rapidly in the block and head, look for water leaking out though one or more exhaust or intake ports. If water is leaking from an intake or exhaust port, it may be impossible to see exactly where the water is originating, but a defective block would definitely be indicated and the block would have be removed from the engine and taken to a machine shop for evaluation.

Best regards,

Don Moyer
Reply With Quote
Reply

Tags
None

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Moderation Tools:
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Removing the engine from your boat Don Moyer General Interest 13 06-27-2008 11:06 AM
Overheating problems jdaly986 Cooling System 1 01-16-2008 10:32 AM
Engine dies under load. Unregistered General Interest 2 08-20-2005 03:35 PM
Engine dies after it warms toscaindub Troubleshooting 2 08-13-2005 03:39 PM
Engine woes Jacob Wenegrat Troubleshooting 5 07-14-2005 09:33 PM


All times are GMT -4. The time now is 07:38 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.


Universal® is a registered trademark of Westerbeke Corporation

Copyright © 2004-2024 Moyer Marine Inc.

All Rights Reserved