Exhaust Manifold bolts

[ksully333]

Hi everyone, new here, have a VP 4.3 gxi motor, going to be replacing the risers and manifolds soon, looking to verify bolt size and thread in order to get right size tap to clean out block threads, first time doing this myself. Going to be using Barr instead of OEM, should I use there gaskets or VP, thanks in advance

 

[Scott Danforth]

Manifold to block will be 3/8-16 or M10 depending on year

 

[ksully333]

Manifold to block will be 3/8-16 or M10 depending on year

Thanks Scott, it's a 2006, appreciate your help

 

[Scott06]

Hi everyone, new here, have a VP 4.3 gxi motor, going to be replacing the risers and manifolds soon, looking to verify bolt size and thread in order to get right size tap to clean out block threads, first time doing this myself. Going to be using Barr instead of OEM, should I use there gaskets or VP, thanks in advance

Barr is very good I bought manifolds and elbows they came with bolts. Their gaskets are good too

 

[ksully333]

Got the elbows and one manifold off today, the starboard side. Went after that one first, had the most surface rust. Bolts came out after a week of daily penetrating spray. Picked up extra long bolts, cut heads off, to hold in place as many here suggested. Found some rust inside the exhaust gas sidewalls but no evidence of leaks on the gasket. There is some rust on the valves, looking for input on how bad this might be.

 

[Lou C]

Those look like the exhaust has been leaking for quite a while. The Barr gaskets are good I installed a set 5 years ago and had to remove the manifolds to get at the steering actuator and no leaks & no rust on the exhaust ports or valves

 

[ksully333]

Thanks Lou C, bases on the attached pics, do you think there's any cause for concern, anything I should do before bolting new manifolds on. Looks like the leak started at the elbow gasket. Purchased boat end of last season, replacing what's needed

 

[Lou C]

With these it’s hard to see a leak path till you clean off the old gaskets. What’s important:
Check the sealing surfaces of the manifolds & elbows with a straight edge & feeler gauges you want them flat & level to less than .002”. If they need to be decked you can take them to a machine shop or do it yourself carefully with a large sanding block or a mill bastard file. You can used the better Volvo Penta gaskets with the recommended copper spray sealer. Make sure to follow the VP instructions carefully. Then you should have no leaks.
Or you can use the Barr gaskets, that’s what I did with mine & I used Permatex Aviation sealer on the gaskets. 5 years later and no leaks.
You can see the effects of leaks on the spark plugs. I’d change what’s in there for AC Delco Marine plugs, in 20 years of salt water use I’ve never had one rust like those.

 

[Lou C]

You want your exhaust ports to look like this (when I as changing my manifolds back in 2011, for the second time) see how they are grey in color with no rust. The rust on the cyl head is just from trapped moisture (condensation, damp climate) from the gasket. This is when I still had the old style OMC one piece batwings which had no gasket to leak. When that pic was taken it had been used in salt water for over 10 years.
Just make sure to carefully check the sealing surfaces, remove all paint, make sure they are flat & level to less than .002", and torque to about 25 ft lbs.
I used the longer bolt with the head cut off trick (also cut a slot in the end for easy removal) to line everything up, makes it much easier. By the time the second pic was taken (2017) I had replaced the cyl heads with reman ones, due to an overheat in 2013.

 

[Lou C]

As far as how bad the rust on the valves is, a compression test will tell you if one or more are not seating, so will a backfire through the intake. If so you might need to have a valve job done. Not a big deal to pull the heads on one of these. Just a few hrs work once you get the exhaust/carb/distributor off.
In the future monitor your exhaust system for leaks and (if a carbed engine) fog the engine for winter storage, that helps keep the valves from rusting in storage.
If you have to do a top engine overhaul, you will start out with this.....
and hopefully wind up with this

 

[dubs283]

Those exhaust ports look nasty and the valve seats are most likely toast. Water in the combustion chamber causes severe damage in a short time. Based on the photos it appears this is a salt water engine?

As Lou stated a valve job is most likely required at a minimum, would think there is damage to the intake valves and possibly pistons as well.

 

[Scott Danforth]

Got the elbows and one manifold off today, the starboard side. Went after that one first, had the most surface rust. Bolts came out after a week of daily penetrating spray. Picked up extra long bolts, cut heads off, to hold in place as many here suggested. Found some rust inside the exhaust gas sidewalls but no evidence of leaks on the gasket. There is some rust on the valves, looking for input on how bad this might be.

valves dont look bad, look like it was running a bit warm. you also have some carbon build-up

 

[cptbill]

Like Scott said the valves are pretty normal looking. My thing with VP's is not using that factory metal gasket that goes between the manifold and the riser, every time I've had a failure it's been the metal gasket that failed not the riser or manifold

 

[ksully333]

As far as how bad the rust on the valves is, a compression test will tell you if one or more are not seating, so will a backfire through the intake. If so you might need to have a valve job done. Not a big deal to pull the heads on one of these. Just a few hrs work once you get the exhaust/carb/distributor off.
In the future monitor your exhaust system for leaks and (if a carbed engine) fog the engine for winter storage, that helps keep the valves from rusting in storage.
If you have to do a top engine overhaul, you will start out with this.....
View attachment 358553 and hopefully wind up with this
View attachment 358554View attachment 358555

Nice job on the motor, looks fantastic. Will definitely take your advice and a compression test done. Cleaning mating surfaces on the block, painting where needed, will be putting the manifolds on tomorrow. Can't thank you enough for your help and guidance, thanks again Lou

 

[ksully333]

Nice job on the motor, looks fantastic. Will definitely take your advice and a compression test done. Cleaning mating surfaces on the block, painting where needed, will be putting the manifolds on tomorrow. Can't thank you enough for your help and guidance, thanks again Lou

Capt Bill, Scott, I've been so concerned these past few days after seeing the rust inside, hearing from you both as well as LouC have relieved alot of stress here. My wife was ready to hang me for buying someone else's problem. Thanks so much, don't know what I'd do without your wealth of knowledge, thanks again

 

[ksully333]

Dubs283, thanks for your reply, hoping to get this season in and then get the valve job done for the next. Season is fairly short up here, so hoping it holds up till September, thanks again

 

[Lou C]

If the comp test is good and it runs well you don't have to do a valve job till needed. Just monitor the exhaust for leaks. it is one of the most common causes of inboard engine problems.
My 1988 OMC had the one piece bat wing manifolds, these had no joint to leak and I never had leaks into the cyls with them. Some did have problems, as did those with the Mercruiser version of the same thing, but I didn't. When these became NLA I had an extra set but after I used those as long as is wise here in salt water (5-7 seasons) I had to convert to the same style Volvo used up until the cat converter exhaust. In addition, if this is a fuel injected engine, there is a different procedure to fog it for winter storage than for carbed engines like mine. That also will reduce internal corrosion that is caused by condensation. Here's an old pic with the OMC batwings.

 

[ksully333]

Thanks Lou, still have lots to yet on this motor before I get to start it. Previous owner wasn't handy and was upfront about not staying up on the maintenance. The list includes replacing the fuel pump assembly, high pressure pump was pitted on the casing and started spraying fuel on the motor on our second time out, changing impeller, thermostat, spark plugs, cleaning fuel regulator, wire wheel the rust of the pulleys and painting. Having the bellows and Gimbel bearing checked out at a local mariner and sanding/painting out drive. Just need it to stop raining every darn weekend, if only I was retired, haha. Thanks again, will definitely let the group know how it all goes