7.4 EFI modification questions ??

[37 Dancer]

I have a pair of 1995 7.4 EFI motors in my 370DA. Last season I had a problem with one leaking tranny cooler. When I pulled the coolers/exchangers off ....I found I had a limited production cooling system ( according to Mercruiser)....no longer available. My engine /tranny/oil cooler were a three in one unit. I searched the net last season and all winter.... unable to find NEW REPLACEMENTS. So I decided to have new ones built by a local shop ( Lenco Inc ) What I ended up doing was spliting them into 2 seperate units......one engine cooler.....and one oil / tranny cooler. I also decided to increase the diamater of the cooler tubes. The new engine coolers went from a 4" tube to a now 5" tube also 2" longer. The seperate oil/tranny coolers went from a 1 3/4" to a now 2 1/4 " tube.

My question is does anyone have the old limited production coolers ?? and if you changed them what was your solution ?

My project is to install them this week.....and hope they work OK.....and not make the engine run too cool...I plan on installing all new hoses and 160 degree thermostats.

Anyone have any advise/suggestions ???

Here's a pic of the original 3 in 1 coolers
...the top 4" tube is the engine heat exchanger/cooler
...the bottom are the engine oil (left) and the tranny cooler ( right) .......all ONE unit.

Thanks.............

 

['Bright Ayes']

Don: I'm so used to seeing "Double D" on the boatered.com site I was almost going to tell "37 Dancer" to get in touch with you til I realized it was the same person!! :smt021 :smt043

Good Luck with the change!

OJ

 

[37 Dancer]

OJ......yes I have a split personality ... :smt014

We'll see how it works out.....Monday I plan to install all the new coolers on both motors.....and dewinterize them. :thumbsup:

 

[fwebster]

Looks like a plan to me.......and a better one than Merc had in the beginning, too.

I do have an observation and a question on temperatures and capacity........Having too much capacity is much better than having just enough. The thermostats will hold the operating temps where they are supposed to be. But 160 degrees seems pretty cool for an EFI engine doesn't it? I thought they usually ran more like 180-195..........If you have checked the spec, great, if not, I'd use the recommended thermostat for your engines so they will be as efficient as possible.

Congratulations on thinking outside the box....................

 

[37 Dancer]

Frank....like always.....thanks for your reply.

Yes......I think that 3 in 1 cooler was a blunder on the part of Mercruiser. :smt009

Originally I wanted to replace both thermostats with 140's....thinking cooler would be better :smt017 ..... but your correct.... My mechanic contacted Mercruiser and was told that the EFI motors require a minimum 160 degree thermostat to run properly and efficiently...due to fuel and block temp sensors. So I have 2 new 160's to be installed.

Hopefully all work together.

 

[37 Dancer]

UPDATE.......

Went and picked up my ( 4 ) new coolers this morning.....What a work of art..... I'm very pleased with their work.

These are the new 5" engine cooler/exchanger:

These are the new 2 1/4" engine oil & tranny fluid cooler :...

I spent the day installing the coolers...new 160 degree thermostats....and all new hoses.....they fit perfect.
Tomorrow I fill exchanger with antifreeze....open my seacocks......and fire them up. :thumbsup:

Hope all goes well.........

 

[Dave B]

Don -

How the heck are you? Did my wife ever send you $$ for that table leg? If not, let me know and I will make good.

Anyway, I noticed one of these on e-bay -- looks like what you are talking about. Hope it helps.

Regards,

David

http://cgi.ebay.com/ebaymotors/Merc...104QQitemZ190096716696QQrdZ1QQsspagenameZWDVW

 

[37 Dancer]

Dave........All is good !!. How the heck are you ???? I was wondering what happen to you buddy. I hope everything is OK.
Don't worry about the table leg.......I had 2 of them.....and I'll never use the one I have left. Im glad you could use it.

I seen that cooler on e-bay.......its just the one cooler ( oil or tranny ) . Thats similar to what I used at the end of last season ...when my tranny cooler failed.... to get me thru till I winterized.

There all new now.....and they work sweat. :thumbsup:

Are you unwrapped and in yet ????

 

[Dave B]

Don -

Great to hear from you, too. I cut the shrink last week but won't go in for 2 weeks or so - I have to make a 130 mile trip to Cleveland as soon as I splash (we moved over the winter) and there is still ice on the lake. That, and I am taking few of a number of minor annoyances (weak starter, broken paddle wheel on the speed sensor, etc.) so I have to wait to get parts back before we go in.

I hope all is well with you. Do give a shout if you are in the Cleveland area.

Best regards,

David

 

[37 Dancer]

Dave.....Congrats on the move.....hope it all works out for you. :thumbsup:

Get that little stuff fixed and enjoy some boating.

Thanks for the invite.......I will do if I come your way.