Logo
FULL SITE MENU

Thermostat Replacement 85 90hp E90TLCOS

S

Sam110

Regular Contributor
What is the EASIEST method to access the thermostat cover bolts? As I understand the service manual it is done while the power head is removed. I do not have the luxury of the equipment / shop environment or experience to tackle such 'extensive' repair. I have watched a "YouTube" video of an owner who cut an opening in the lower cowling to access the cover bolts and afterwards replaced the cut out piece with the help of some BJ Weld. This seems to me to be the easiest way possible for someone with limited resources.

https://www.youtube.com/watch?v=ms7S-sUocwc&t=389s

I guess my concern is what is the possible and unforeseen downside of weakening the lower cowl in this way .. other than cosmetic? Is there a better "EASY" way?
 
They built them like that for some 20 years.----Dealers would have complained if it was an impossible job !!------So go for it and change them out.-----And there is no need to " cut and chop " on this job at all.-----Done the job numerous times without molesting the lower cowling.
 
Remove the rear plastic cover to gain access, use offset box wrench. Hellava job but as "racer" says, it's been done many times by all of us.

Suggestion... hold the assembly together (everything except the springs) with tie straps, wire, whatever when re-installing (The loose springs aren't too much of a problem to add in there when installing) so as to make threading those three bolts in a bit, after which you can cut the tie straps or whatever away to tighten the bolts the rest of the way.
 
Pulling the power head is the 'text book' and I suppose the ideal way of doing this job but I cringe with each bolt that has to be removed out of the thought of them breaking off and the subsequent problems that arise. I'm not 'shop' equipped (space or tools) to deal with any such unforeseen issues and would rather avoid that possibility if at all possible. I believe Joe that I'll go with your method first, but as for my initial question .. Are there concerns engine performance wise which you might foresee cropping up 'down the road' by cutting the lower cowling?
 
Thanks Joe for the suggestion and racer for shaming me away from "chopping up" my lower cowling. I followed Joe's method by modifying a wrench and had no problem at all. The bolts backed out without a fight. I appreciate the help.
 
Sam110 said:
What is the EASIEST method to access the thermostat cover bolts? As I understand the service manual it is done while the power head is removed. I do not have the luxury of the equipment / shop environment or experience to tackle such 'extensive' repair. I have watched a "YouTube" video of an owner who cut an opening in the lower cowling to access the cover bolts and afterwards replaced the cut out piece with the help of some BJ Weld. This seems to me to be the easiest way possible for someone with limited resources.

https://www.youtube.com/watch?v=ms7S-sUocwc&t=389s

I guess my concern is what is the possible and unforeseen downside of weakening the lower cowl in this way .. other than cosmetic? Is there a better "EASY" way?
Click to expand...

I thought the same as you, and did cut the cowling before the guy in the video did it or before he made the video. Here's the link:

http://forums.iboats.com/forum/engi...ermostat-replacement-on-1990-115-v4-crossflow

Cutting it as I did it, does not weaken the cowling, as I only cut a square into it. Now I can change my thermostat in 15 minutes.

With the video link you posted and my thread link you can do an even better job than both of us.
 
Last edited:
I watched the video link, I had seen it before, but wanted to review it for you.

- I like his use of the Dremel, it is easier to control than the large Sawzall and angle grinder that I used.

- He held the cutout bracket in place with JB welded flaps , but he never finished the job. I'm certain he ended up doing something else. Mine is held by an aluminum flat piece that goes across the whole back of the cutout piece and extends out the two sides where it is held on both sides with machine screws, washers and locknuts (see the pictures). The middle screw holds the aluminum flat piece. I do not want to lose that part, so I mechanical hold them with three machine screws, locknuts and washers.
 
Last edited:
Klink, Thanks for the answer to my initial question. Your cut out in the picks doesn't look bad at all ! I almost went that route but was nervous about making it look bad. Like you said the guy in the video I posted never showed a final pic. He didn't answer my question in the comments either about causing other unforeseen problems. After making the cut I had planned on resecuring the 'panel' piece like you did but I was going to use rivets. They could easily be drilled out or cut out the next time the job needed done. I do have to admit that getting all those pieces back in that cramped space while fighting that spring tension was a real pain but it's in. Next time I just may resort to making life a bit easier with my dremel.
 
Did you disassemble the engine or use the squeeze in method? I didn't see how it could be squeezed being that mine is a bubble back, the room just was not there. Is yours a bubble back? See the bubble in the middle over the thermostat area:

Bubble back example.jpg
 
Last edited:
Sam110 said:
After making the cut I had planned on resecuring the 'panel' piece like you did but I was going to use rivets. They could easily be drilled out or cut out the next time the job needed done.
Click to expand...

My method is easy to remove and replace anytime. Just remove three nuts. As far as the cutout slot, water does not get up that high so I never caulked it. Like I said, OMC could have easily made a removable cover for the repair.
 
Agreed, OMC didn't seem to put much thought into owner maintenance with this issue. Without a shop like environment to work in, pulling the power head was just too much of a job for me to tackle in my environment this time of year. To answer your question, NO, my motor is not a 'bubble back'. I hadn't noticed previously but the parts diagram here on site shows mine to be a 'bubble back' manifold. ?? I'm guessing it's the same reason a Ford truck I once owned had the previous years front end, it was made in the 1st half of the year. Those later in the year had the newer style. Maybe someone reading this thread can explain?? Racer? Joe? Kim? anyone?
 
The 1985 90hp did not have the tuned exhaust setup via the "bubble back" in 1985 or in any other year. That did not come into place until the following year when that 1986 model was upgraded to 110hp.... the 90hp of 1986 continued to have the standard flat back-plate exhaust setup.
 
Bubble back exhaust was first used on the 1973 135 hp models.-----Used on the higher rated V-4 blocks untill the last ones in 1998 I believe.-------They show it on all the crossflow V-4 models in the parts book just because they can !!-----Saves putting out more parts books !------On " looper " blocks the tuned exhaust was part of the block itself.
 
Last edited:
I see. Well that answers my next question as to the "why" they were bubbled outward like that .. a tuning feature. Thank you.
 
Klink said:
Did you disassemble the engine or use the squeeze in method? I didn't see how it could be squeezed being that mine is a bubble back, the room just was not there. Is yours a bubble back? See the bubble in the middle over the thermostat area:

View attachment 16897
Click to expand...

If you are working with a Crossflow head that has the larger exhaust housing, remove it.

Removal of the thermostat housing with the exhaust system in place is certainly doable, but getting the springs and thermostats to align without falling out on reinstallation is a bit of a chore without getting the larger exhaust manifold out of the way.
 

Attachments

  • E6A41B9B-DA9F-41A3-9E2A-8F2B851708BD.jpg
    E6A41B9B-DA9F-41A3-9E2A-8F2B851708BD.jpg
    77.6 KB · Views: 102
Back
Top