PDA

View Full Version : LT1 overheating


formosa
07-30-2011, 09:48 PM
Thanks for all the help so far with my 200VRS LT1. The boat is overheating - keeps going past 200 when I shut it off (at 200). I removed both thermostats. New impeller. Disconnected all hoses to check for flow. Previously I was using a hose attached to the intake hose... so put the intake hose in a bucket (and it took in the water rapidly). Water is getting past the cooler as well (removed the hose connecting to the block and water going through that does not seem restricted).

What is really concerning is looking at the back of the boat only the left/passenger side exhaust is expelling water. The right side does not. The manifold and riser get much hotter than the left side. I removed the plug on the manifold and there's plenty of water coming out of the manifold. Although removing the small water hose on top of the riser and there's practically nothing going on there (at best a trickle). This must be a problem?

The manifold that is expelling water through the exhaust - there is a stream of water going through the small hose as well as from the brass fitting.

Is my riser and/or manifold clogged? What would stop water from exiting the riser as again the manifold is full of water (know this by removing the front plug)?

I have not changed the water pump. If the water pump was bad - why would the left exhaust expel water as it should?

Thanks for all your help.

thatsmrmastercraft
07-30-2011, 09:55 PM
I know nothing about the LT1, but it sure sounds like you have an obstruction issue. Someone with some proper knowledge on this will be along with some answers. Good luck.

jakethebt
07-30-2011, 10:30 PM
Do some searching on here on LT1 over heating problems. Seems like there have been a few threads on it. Seems like there was an issue of air getting trapped in the system and some guy had a way fix it by switching a few tubes and hoses. I seem to remember it working for a lot of people.

formosa
07-31-2011, 01:25 AM
Thanks, I did search earlier - although your post prompted me to search for "LT-1" (was using LT1) and that produced some more posts, one talked about a clogged riser. I'm going to remove the riser and try to clear any blockage.

jakethebt
07-31-2011, 09:01 AM
This is the one that I was thinking of...

http://mastercraft.com/teamtalk/showthread.php?t=31626&highlight=lt-1

The thread is a bit different but the info sound like it has identified the cooling problem and a fix. There are a 100 other threads on LT-1 overheating... so if this does not work maybe one of the others will.

formosa
07-31-2011, 09:31 AM
Thanks. I did find and read this previously - in my case the motor never had a chronic cooling issue (that I know of) and always ran at 160 degrees. That is until the boat was stolen/sunk and now I'm in the process of putting back on the water. I will change these tubes at some point, in the meantime want to get the system working as intended first. With no water coming out the driver side exhaust ....

JimN
07-31-2011, 09:38 AM
Thanks for all the help so far with my 200VRS LT1. The boat is overheating - keeps going past 200 when I shut it off (at 200). I removed both thermostats. New impeller. Disconnected all hoses to check for flow. Previously I was using a hose attached to the intake hose... so put the intake hose in a bucket (and it took in the water rapidly). Water is getting past the cooler as well (removed the hose connecting to the block and water going through that does not seem restricted).

What is really concerning is looking at the back of the boat only the left/passenger side exhaust is expelling water. The right side does not. The manifold and riser get much hotter than the left side. I removed the plug on the manifold and there's plenty of water coming out of the manifold. Although removing the small water hose on top of the riser and there's practically nothing going on there (at best a trickle). This must be a problem?

The manifold that is expelling water through the exhaust - there is a stream of water going through the small hose as well as from the brass fitting.

Is my riser and/or manifold clogged? What would stop water from exiting the riser as again the manifold is full of water (know this by removing the front plug)?

I have not changed the water pump. If the water pump was bad - why would the left exhaust expel water as it should?

Thanks for all your help.

Remove the small hoses from the engine, one at a time. Make sure they're not clogged. Look for pieces of impeller where they attach to the heads, etc.

formosa
07-31-2011, 06:27 PM
Thanks JimN and jake ... we found the problem. Removed the riser - no blockage --- put the hose into the exhaust hose --- it filled up and no water came out of the exhaust! A peek up into the exhaust at the transom and the right muffler was completely clogged with a fiberglass disc from the muffler. I don't even see how the boat ran. Anyways removed that and she started up and ran 120 degrees (recall I took the thermostats out) --- constant, and both exhausts blowing out hot water about the same --- as well as both risers are reasonable temps. Great!!!

milkmania
07-31-2011, 06:56 PM
Thanks JimN and jake ... we found the problem. Removed the riser - no blockage --- put the hose into the exhaust hose --- it filled up and no water came out of the exhaust! A peek up into the exhaust at the transom and the right muffler was completely clogged with a fiberglass disc from the muffler. I don't even see how the boat ran. Anyways removed that and she started up and ran 120 degrees (recall I took the thermostats out) --- constant, and both exhausts blowing out hot water about the same --- as well as both risers are reasonable temps. Great!!!

http://img.xcitefun.net/users/2011/05/247750,xcitefun-congrats.gif

JimN
07-31-2011, 07:25 PM
Thanks JimN and jake ... we found the problem. Removed the riser - no blockage --- put the hose into the exhaust hose --- it filled up and no water came out of the exhaust! A peek up into the exhaust at the transom and the right muffler was completely clogged with a fiberglass disc from the muffler. I don't even see how the boat ran. Anyways removed that and she started up and ran 120 degrees (recall I took the thermostats out) --- constant, and both exhausts blowing out hot water about the same --- as well as both risers are reasonable temps. Great!!!

You want to put the thermostats back in.

formosa
07-31-2011, 09:46 PM
Will do - I read your previous posts on this. Thanks again.

jakethebt
07-31-2011, 11:11 PM
JimN... you were a key poster in the thread i linked to... at first you were not too hip on the ideas in that thread (understandably so as the author was a bit bold). Now that some time has passed, do you have any comments on the validity of the thread? Do you think that the re-plumbing of the cooling system is a good idea or does it work better than stock, or leave well enough alone?

formosa
08-11-2011, 10:11 PM
Now water is in the oil. It's milkshake. After reading here - I ran a compression test on the cylinders (ordered gauge from Amazon). Every cylinder is 170-175 lbs _except_ cylinder #2 right bank - it builds plenty of pressure on the gauge, problem is it keeps going 175...200...225... when I pull the compression gauge off - there is water. This is the same side that had the plugged exhaust. There was also water on the plug, and when I initially turned the engine over, water came out of the plug hole.

Could a leaking exhaust riser do this? Or is this head gasket (and heads checked) time? Also would you recommend replacing both head gaskets - or is this a case of if it's working leave it alone?

Thanks -

j.mccreight@hotmail.com
08-11-2011, 10:25 PM
Definatly a head gasket, no need to do the other side if all cylinders had good even compression.

JerryW
08-11-2011, 10:31 PM
A friend just had a very similar issue with a 1995 225 VRS with an LT-1. Since the heads are aluminum, overheating can quickly warp the head, and it may be more than just replacing the head gasket. Have the head checked for warping, and if it is, the best bet is to have both heads shaved, and all related gaskets replaced.

JimN
08-12-2011, 01:03 AM
JimN... you were a key poster in the thread i linked to... at first you were not too hip on the ideas in that thread (understandably so as the author was a bit bold). Now that some time has passed, do you have any comments on the validity of the thread? Do you think that the re-plumbing of the cooling system is a good idea or does it work better than stock, or leave well enough alone?

The3 stock exhaust usually works well unless the raw water supply is decreased or blocked and water can't cool the exhaust gases- then, the muffler falls apart. The problems are all related, IMO. I have never seen a fiberglass muffler fall apart on its own and the only other failures I saw were from someone doing flat spins and water bypassing the flappers.

JimN
08-12-2011, 01:06 AM
Now water is in the oil. It's milkshake. After reading here - I ran a compression test on the cylinders (ordered gauge from Amazon). Every cylinder is 170-175 lbs _except_ cylinder #2 right bank - it builds plenty of pressure on the gauge, problem is it keeps going 175...200...225... when I pull the compression gauge off - there is water. This is the same side that had the plugged exhaust. There was also water on the plug, and when I initially turned the engine over, water came out of the plug hole.

Could a leaking exhaust riser do this? Or is this head gasket (and heads checked) time? Also would you recommend replacing both head gaskets - or is this a case of if it's working leave it alone?

Thanks -

Drain the oil, pull the fuel pump fuse and do the compression test dry. Do a vacuum test, too. If you see anything bad, it will have to be taken apart to find the cause. A bent valve will cause some of these same issues but water getting into the cylinder is the reason your compression rose and it could have caused the bent valve.

blackcreek
08-13-2011, 03:14 PM
Now water is in the oil. It's milkshake. After reading here - I ran a compression test on the cylinders (ordered gauge from Amazon). Every cylinder is 170-175 lbs _except_ cylinder #2 right bank - it builds plenty of pressure on the gauge, problem is it keeps going 175...200...225... when I pull the compression gauge off - there is water. This is the same side that had the plugged exhaust. There was also water on the plug, and when I initially turned the engine over, water came out of the plug hole.

Could a leaking exhaust riser do this? Or is this head gasket (and heads checked) time? Also would you recommend replacing both head gaskets - or is this a case of if it's working leave it alone?

Thanks -

The overheats are not a good sign but I would sure check that exhaust manifold first. My last boat was a ski supreme with chevy 350 and had water in the oil from a cracked exhaust manifold. The boat would run ok once reved up but at idle it would miss and once you shut it down the water would leak down into the cylinder past the rings and into the crankcase. Pull the manifold and look for water/rust tracks inside.Or,you could drain the manifold and pull the water hose to it then do another compression check, if you still get water it is coming out of the block through a gasket or cracked head.

wtrskr
08-14-2011, 10:53 PM
If the exhaust tube was blocked, couldn't water have then filled that whole area and forced its way back through the riser and exhaust manifold into your cylinder? Can you find out if new water is still dripping into the cylinder? I had a blown head gasket and after running for a while then letting it sit, the cylinder would fill back up.

Maybe my logic is wrong but it seems possible that you could remove your plugs and blow out the water then change the oil and be done. JimN's comment about never seeing a fiberglass muffler fall apart for no good reason makes that a lot less probable. I thought I'd bring it up though because of the exhaust manifold comments.

formosa
08-16-2011, 09:29 AM
I will check the manifolds - and run the compression test dry. It is happening after it's been unblocked and I blew out the water with the plugs removed. I also changed the oil. The sign for me is that the oil "level" is rising and that tells me more water is still coming in. Thanks for the info and ideas ...

formosa
07-06-2012, 06:17 AM
I've been out of the country for a year. Update: Replaced the exhaust riser gasket. In my haste last time to find the cooling problem I did not properly reassemble this nor did I have a new gasket on hand. I was incorrectly thinking at the exhaust side a solid seal was not critical as water wouldn't/couldn't come back into the exhaust side). Couple that with not "seeing" any water leak externally ...

When dissembling again; I did see a small "puddle" of clear water at the bottom of the exhaust manifold ... obviously water had traveled that direction.

Completely scraped off old gasket, cleaned both surfaces - new gasket and sealer. After changing the oil and filter a few times, running the boat for a couple of hours: oil remains clear and steady. Compression tests are similar to the other bank... and no water in the previously offending cylinder.

Just throwing this out there in case anyone else takes apart the riser and then has issues ...

Thanks again for all the help.