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Volvo AQ125A Head

J

jcampbell

Regular Contributor
I have a Volvo penta AQ125A 4 cylinder. I pulled the manifold off and noticed the 4th exhaust port is pretty bad. I have the casting number its a 1000398.

I'm in the process of looking for a replacement head but they seem hard to find or are big $$. So any help there would be great.

I was also wondering if I can put the new manifold on and use the boat for 2 or 3 more trips before i'm done for the season and start my river fishing or is it too far gone to function properly. I mostly fish in salt water with the occasional fresh water lake boating.

For the most part ive been able keep up on corrosion issues but this one caught me off guard when a chunk of the manifold came off and i wasn't getting any exhaust through the out drive. I think 7 years was to long on that manifold and that's just how long ive owned it. The new manifold seems beefier then the one i took off. the new one is a barr.

Any advice or assistance would be appreciated if you think its ok to use it for a couple more trips with a new manifold. I can handle the exhaust leak noise. And as to were a good source of a head.
 
I took some pictures of the 4th port on the head.

IMG_01061.jpg



IMG_01072.jpg
 
Bump

I was wondering i can find a head with casting number 1000531 easily but mine is 1000398 i was wondering if i can use the 531 head instead of the 398?. Also still curious if i can use the current head for 2-3 more trips before i do the change out?

I can handle the exhaust noise and i dont keep it fully covered. I already have a new manifold ready to go.
 
Slow day on the VP board, people must be out boating :)

I am in the same 'boat' as you so to speak. Lucky my PO threw in another motor with the boat when I bought it. It was actually in better shape than my original. I've been harvesting parts as I need them. I found my #4 port was in just as bad of shape as yours when I swapped the ex. manifold. Last summer I took some exhaust putty and high temp exhaust wrap I got form NAPA. I slathered the putty around the connection to the head and manifold. Then slathered more on the wrappping and wrapped it around a couple of times. Then I got some tin and wrapped around that and a couple of 4" hose clamps to hold everything in place. So far so good, I've put 300 miles on so far since without leaks. I think if you want to get another couple of trips out before summer ends this might work for you. But this is just a temporary bandaid as I took the head off the spare motor and had it gone through by the machine shop and had it checked out, cleaned up, decked, and all rubber replaced. I just got it back so when i get a spare weekend this winter I will swap that and all will be good.

BTW there is a guy up in Snohomish county that doe "the fix" by coring out the port and putting in an insert but yours, like mine, is too far gone. He charges $300 if you haul the boat to him. My head only cost $200 to refurbish and $60 for a gasket set.

Also you can use a car head, you will have to research which engine crosses over but have a machine shop go through it and put your marine cam in when they do. Frankly these engines are virtually bullet proof all except for the aluminum head. As long as there is coolant in the cooling system you won't have to worry about freeze damage, and if the oil have been changed regularly I think the bottom end should be a good shape.
 
Last edited:
pugetsounder said:
Slow day on the VP board, people must be out boating :)

I am in the same 'boat' as you so to speak. Lucky my PO threw in another motor with the boat when I bought it. It was actually in better shape than my original. I've been harvesting parts as I need them. I found my #4 port was in just as bad of shape as yours when I swapped the ex. manifold. Last summer I took some exhaust putty and high temp exhaust wrap I got form NAPA. I slathered the putty around the connection to the head and manifold. Then slathered more on the wrappping and wrapped it around a couple of times. Then I got some tin and wrapped around that and a couple of 4" hose clamps to hold everything in place. So far so good, I've put 300 miles on so far since without leaks. I think if you want to get another couple of trips out before summer ends this might work for you. But this is just a temporary bandaid as I took the head off the spare motor and had it gone through by the machine shop and had it checked out, cleaned up, decked, and all rubber replaced. I just got it back so when i get a spare weekend this winter I will swap that and all will be good.

BTW there is a guy up in Snohomish county that doe "the fix" by coring out the port and putting in an insert but yours, like mine, is too far gone. He charges $300 if you haul the boat to him. My head only cost $200 to refurbish and $60 for a gasket set.

Also you can use a car head, you will have to research which engine crosses over but have a machine shop go through it and put your marine cam in when they do. Frankly these engines are virtually bullet proof all except for the aluminum head. As long as there is coolant in the cooling system you won't have to worry about freeze damage, and if the oil have been changed regularly I think the bottom end should be a good shape.
Click to expand...

Thanks for writing. I did manage to find a head online looks to be in good shape about the only thing I can see wrong is it doesn't have cam and one of the studs for the valve cover is missing bbut for a 100 clams it should be ok, the exhaust ports don't even look like they seen any wear.

I used to use quick steel to bandage the exhaust leak on mine seemed to hold up ok for me. These are pretty robust engines and take a beating an still keep ticking. Now my pocket book begs to differ with all the repairs I did this year. I guess I now have to be more diligent about puling the manifold off the boat every 3 years. Im not sure how often this should be done as I average about 20-40 hours a year on the boat engine run time.

Here is a photo of the new to me head I ordered.

 
If you take the head into a machine shop they will pull the studs out anyway. I'm sure your other head will do for doner parts, ei. camshaft extra studs, etc. I took mine to Earl's in Burien right on 1st Ave South. thye knew all about these Volvo engines. They even driected me to buying the proper seals online to bring in with the head. They did a great job. I'm sure there are good machine shops out where you live. They need to know the specs for the clearances when they set the camshaft.

I think freshwater heads aren't as prone to the corrosion as boats used in saltwater. I just try and flush mine out as best I can and hope it doesn't corrode anymore. I can't wait to find time this winter to swap to the new head.
 
That boring of the rear exhaust port was a Volvo Penta fix many, many years ago. I had access to this tool in my early days when working at a V/P specialty shop in SoCal. I must have done 50-75 of them. It was a cool tool as it bolted to the head on the exhaust studs and you just turned the bit with a big wrench. It bored to an exact point and no further. Pull the borer off and smack a SS collar in the hole and it was done.
It most definitely wouldn't have fixed that one in the pic but it made brand new of many heads.
 
After getting the new head in I noticed that the 3rd and 4th cylinder were repaired but unless you actually felt the ridge and noticed the un-even welding on by the spark plug on the 4th cylinder you would never know. I also noticed 2 or 3 heilicoils in the head as well. Otherwise appears to be in good shape will have to see what the head shop says. I think I might bring it to centerline machine shop in Puyallup they were recommended by some other people around here if they didn't close down when napa took them over.
 
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