AQ130 Exhaust port corrosion

"I have stripped both my engin

"I have stripped both my engines because they're now 28 years old and smoke a little from the breathers. I was amazed to find that the bearings and pistons are all original and will only require honing and piston rings as well as new shell bearings.
When overhauling the cylinder heads I found the rear exhaust port badly corroded. The port was reduced in size by almost a third, but had no signs of any corrosion to the valve, piston or bore. The head was pressure tested and water is not coming from the water jacket.
I can only assume that there is a leak in the exhaust manifold but am finding it difficult to test.
Does anyone have any experience or ideas before I buy a new manifold?
Thanks
Phill"

your exhaust manifold is most

your exhaust manifold is most likely corroded. It is a very popular symptom for the AQ's.

"Corrosion around exhaust port

"Corrosion around exhaust ports 3 and 4 is not uncommon, but in your case I think it is not bad for 28 years service!!!

In addition to Ron's suggestion, if your outdrive is a 270, make sure the flapper is in place in the exhaust outlet. And if it is a 280, make sure the exhaust bellows has a flapper installed. The flapper will prevent water ingress in the exhaust, especially when the boat goes astern."

"I replaced my 280 bellows las

"I replaced my 280 bellows last year with the ones with flaps in. The old ones I removed didn't have flaps so maybe that caused the corrosion.
I still need to test these manifolds somehow before I refit them as I dont want to damage my fresh engines.
As for your comments Ron, I guess replacing manifolds is the only option."

"You can take them to a radiat

"You can take them to a radiator shop and have them boiled, but at 28yrs service, I would think replacement is the best option, but you can always try. It may cause pinholes in the manifold though. If it were me (I have to replace mine this spring) I would buy a new one...They run around 240-ish for my AQ125B. Not sure if your 130 takes the same manifold or not. HTH

Ron"

"Exhaust manifolds for AQ130s

"Exhaust manifolds for AQ130s are significantly more expensive than the ones for the OHC Volvos. For some reason, they don't seem to be available aftermarket, possibly because there are not many AQ130s left around compared with the OHC versions."

I had the same problem and it

I had the same problem and it was the exaust manifold as the gentlemen have stated above. The channels inside of the manifold were wasted as well as another internal part that was alowing water ingress to #3 and 4 cylinder. Had corrosion on the exaust port that was about 30%-60% on my aq125.